Ontology evolution: a process-centric survey
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paper_title: Ontology change: classification and survey

paper_content:

Ontologies play a key role in the advent of the Semantic Web. An important problem when dealing with ontologies is the modification of an existing ontology in response to a certain need for change. This problem is a complex and multifaceted one, because it can take several different forms and includes several related subproblems, like heterogeneity resolution or keeping track of ontology versions. As a result, it is being addressed by several different, but closely related and often overlapping research disciplines. Unfortunately, the boundaries of each such discipline are not clear, as the same term is often used with different meanings in the relevant literature, creating a certain amount of confusion. The purpose of this paper is to identify the exact relationships between these research areas and to determine the boundaries of each field, by performing a broad review of the relevant literature.
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paper_title: Knowledge Engineering: Principles and Methods

paper_content:

This paper gives an overview of the development of the field of Knowledge Engineering over the last 15 years. We discuss the paradigm shift from a transfer view to a modeling view and describe two approaches which considerably shaped research in Knowledge Engineering: Role-limiting Methods and Generic Tasks. To illustrate various concepts and methods which evolved in recent years we describe three modeling frameworks: CommonKADS, MIKE and PROTEGE-II. This description is supplemented by discussing some important methodological developments in more detail: specification languages for knowledge-based systems, problem-solving methods and ontologies. We conclude by outlining the relationship of Knowledge Engineering to Software Engineering, Information Integration and Knowledge Management.
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paper_title: A Semantic Web Primer

paper_content:

The development of the Semantic Web, with machine-readable content, has the potential to revolutionize the World Wide Web and its uses. A Semantic Web Primer provides an introduction and guide to this continuously evolving field, describing its key ideas, languages, and technologies. Suitable for use as a textbook or for independent study by professionals, it concentrates on undergraduate-level fundamental concepts and techniques that will enable readers to proceed with building applications on their own and includes exercises, project descriptions, and annotated references to relevant online materials.The third edition of this widely used text has been thoroughly updated, with significant new material that reflects a rapidly developing field. Treatment of the different languages (OWL2, rules) expands the coverage of RDF and OWL, defining the data model independently of XML and including coverage of N3/Turtle and RDFa. A chapter is devoted to OWL2, the new W3C standard. This edition also features additional coverage of the query language SPARQL, the rule language RIF and the possibility of interaction between rules and ontology languages and applications. The chapter on Semantic Web applications reflects the rapid developments of the past few years. A new chapter offers ideas for term projects. Additional material, including updates on the technological trends and research directions, can be found at http://www.semanticwebprimer.org.
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paper_title: Towards a framework for ontology evolution

paper_content:

This paper presents design decisions involved in developing an ontology management framework that supports the user in creating and managing the ontology construction process. This framework supports the functions of an object-oriented representation, generic versioning control, and security of ontologies. Details on design considerations for each component within the framework are presented
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paper_title: A model theoretic semantics for ontology versioning

paper_content:

We show that the Semantic Web needs a formal semantics for the various kinds of links between ontologies and other documents. We provide a model theoretic semantics that takes into account ontology extension and ontology versioning. Since the Web is the product of a diverse community, as opposed to a single agent, this semantics accommodates different viewpoints by having different entailment relations for different ontology perspectives. We discuss how this theory can be practically applied to RDF and OWL and provide a theorem that shows how to compute perspective-based entailment using existing logical reasoners. We illustrate these concepts using examples and conclude with a discussion of future work.
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paper_title: Consistent Evolution of OWL Ontologies

paper_content:

Support for ontology evolution is extremely important in ontology engineering and application of ontologies in dynamic environments. A core aspect in the evolution process is the to guarantee consistency of the ontology when changes occur. In this paper we discuss the consistent evolution of OWL ontologies. We present a model for the semantics of change for OWL ontologies, considering structural, logical, and user-defined consistency. We introduce resolution strategies to ensure that consistency is maintained as the ontology evolves.
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paper_title: Ontology change: classification and survey

paper_content:

Ontologies play a key role in the advent of the Semantic Web. An important problem when dealing with ontologies is the modification of an existing ontology in response to a certain need for change. This problem is a complex and multifaceted one, because it can take several different forms and includes several related subproblems, like heterogeneity resolution or keeping track of ontology versions. As a result, it is being addressed by several different, but closely related and often overlapping research disciplines. Unfortunately, the boundaries of each such discipline are not clear, as the same term is often used with different meanings in the relevant literature, creating a certain amount of confusion. The purpose of this paper is to identify the exact relationships between these research areas and to determine the boundaries of each field, by performing a broad review of the relevant literature.
---
paper_title: Ontology change: classification and survey

paper_content:

Ontologies play a key role in the advent of the Semantic Web. An important problem when dealing with ontologies is the modification of an existing ontology in response to a certain need for change. This problem is a complex and multifaceted one, because it can take several different forms and includes several related subproblems, like heterogeneity resolution or keeping track of ontology versions. As a result, it is being addressed by several different, but closely related and often overlapping research disciplines. Unfortunately, the boundaries of each such discipline are not clear, as the same term is often used with different meanings in the relevant literature, creating a certain amount of confusion. The purpose of this paper is to identify the exact relationships between these research areas and to determine the boundaries of each field, by performing a broad review of the relevant literature.
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paper_title: A Framework for Ontology Evolution in Collaborative Environments

paper_content:

With the wider use of ontologies in the Semantic Web and as part of production systems, multiple scenarios for ontology maintenance and evolution are emerging. For example, successive ontology versions can be posted on the (Semantic) Web, with users discovering the new versions serendipitously; ontology-development in a collaborative environment can be synchronous or asynchronous; managers of projects may exercise quality control, examining changes from previous baseline versions and accepting or rejecting them before a new baseline is published, and so on. In this paper, we present different scenarios for ontology maintenance and evolution that we have encountered in our own projects and in those of our collaborators. We define several features that categorize these scenarios. For each scenario, we discuss the high-level tasks that an editing environment must support. We then present a unified comprehensive set of tools to support different scenarios in a single framework, allowing users to switch between different modes easily.
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paper_title: A Component-Based Framework For Ontology Evolution

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Support for ontology evolution becomes extremely important in distributed development and use of ontologies. Information about change can be represented in many different ways. We describe these different representations and propose a framework that integrates them. We show how different representations in the framework are related by describing some techniques and heuristics that supplement information in one representation with information from other representations. We present an ontology of change operations, which is the kernel of our framework. 1 Support for Ontology Evolution Ontologies are increasing in popularity, and researchers and developers use them in more and more application areas. Ontologies are used as shared vocabularies, to improve information retrieval, or to help data integration. Neither the ontology development itself nor its product—the ontology— is a single-person enterprise. Large standardized ontologies are often developed by several researchers in parallel (e.g. SUO1 [9]); a number of ontologies grow in the context of peer-to-peer applications (e.g. Edutella [5]); other ontologies are constructed dynamically [2]. Successful applications of ontologies in such uncontrolled, de-centralized and distributed environments require substantial support for change management in ontologies and ontology evolution [7]. Given an ontology O and its two versions, Vold and Vnew, a complete support for change management in an ontology environment includes support for the following tasks.2 Data Transformation: When an ontology version Vold is changed to Vnew, data described by Vold might need to translated to bring it in line with Vnew. For example, if we merge two concepts A and B from Vold into C in Vnew, we must combine instances of A and B as well. http://suo.ieee.org/ Note that Vnew is not necessarily a unique replacement for Vold. There might be several new versions based on the old version, and all of them could exist in parallel. The labels are just used to refer to two versions of an ontology where Vnew has evolved from Vold. Data Access: Even if data is not being transformed, if there exists data conforming to Vold, we often want to access this data and interpret it correctly via Vnew. That is, we should be able to retrieve all data that was accessible via queries in terms of Vold with queries in terms of Vnew. Furthermore, instances of concepts in Vold should be instances of equivalent concepts in Vnew. This task is a very common one in the context of the Semantic Web, where ontologies describe pieces of data on the web. Ontology Update: When we adapt a remote ontology to specific local needs, and the remote ontology changes, we must propagate the changes in the remote ontology to the adapted local ontology [8]. Consistent Reasoning: Ontologies, being formal descriptions, are often used as logical theories. When ontology changes occur, we must analyze the changes to determine whether specific axioms that were valid in Vold are still valid in Vnew. For example, it might be useful to know that a change does not affect the subsumption relationship between two concepts: if A v B is valid in Vold it is also valid in Vnew. While a change in the logical theory will always affects reasoning in general, answers to specific queries may remain unchanged. Verification and Approval: Sometimes developers need to verify and approve ontology changes. This situation often happens when several people are developing a centralized ontology, or when developers want to apply changes selectively. There must be a user interface that simplifies such verification and allows developers to accept or reject specific changes, enabling execution of some changes and rolling back of others. This list of tasks is not exhaustive. The tools that exist today support these tasks in isolation. For example, the KAON framework [10] supports evolution strategies, allowing developers to specify strategies for updating data when changes in an ontology occur. The SHOE versioning system specifies which versions of the ontology the current version is backward compatible with [3]. Many ontology-editing environments (e.g., Protege [1]) provide logs of changes between versions. While these tools support some of the ontologyevolution tasks, there is no interaction or sharing of information among the tools. However, many of these tasks require the same elements in the representation of change. Imple-
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paper_title: The DILIGENT Knowledge Processes

paper_content:

Purpose – Aims to present the ontology engineering methodology DILIGENT, a methodology focussing on the evolution of ontologies instead of the initial design, thus recognizing that knowledge is a tangible and moving target. Design/methodology/approach – First describes the methodology as a whole, then detailing one of the five main steps of DILIGENT. The second part describes case studies, either already performed or planned, and what we learned (or expect to learn) from them. Findings – With the case studies it was discovered the strengths and weaknesses of DILIGENT. During the evolution of ontologies, arguments need to be exchanged about the suggested changes. Identifies those kind of arguments which work best for the discussion of ontology changes. Research implications – DILIGENT recognizes ontology engineering methodologies like OnToKnowledge or Methontology as proven useful for the initial design, but expands them with its strong focus on the user-centric further development of the ontology and the provided integration of automatic agents in the process of ontology evolution. Practical implications – With DILIGENT the experience distilled from a number of case studies and this offers the knowledge manager a methodology to work in an ever-changing environment. Originality/value – DILIGENT is the first methodology to put focus not on the initial development of the ontology, but on the user and his usage of the ontology, and on the changes introduced by the user. We take the user’s own view seriously and enable feedback towards the evolution of the ontology, stressing the ontology’s role as a shared conceptualisation.
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paper_title: Winnowing Ontologies Based on Application Use

paper_content:

The requirements of specific applications and services are often over estimated when ontologies are reused or built. This sometimes results in many ontologies being too large for their intended purposes. It is not uncommon that when applications and services are deployed over an ontology, only a few parts of the ontology are queried and used. Identifying which parts of an ontology are being used could be helpful to winnow the ontology, i.e., simplify or shrink the ontology to smaller, more fit for purpose size. Some approaches to handle this problem have already been suggested in the literature. However, none of that work showed how ontology-based applications can be used in the ontology-resizing process, or how they might be affected by it. This paper presents a study on the use of the AKT Reference Ontology by a number of applications and services, and investigates the possibility of relying on this usage information to winnow that ontology.
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paper_title: A translation approach to portable ontology specifications

paper_content:

Abstract To support the sharing and reuse of formally represented knowledge among AI systems, it is useful to define the common vocabulary in which shared knowledge is represented. A specification of a representational vocabulary for a shared domain of discourse—definitions of classes, relations, functions, and other objects—is called an ontology. This paper describes a mechanism for defining ontologies that are portable over representation systems. Definitions written in a standard format for predicate calculus are translated by a system called Ontolingua into specialized representations, including frame-based systems as well as relational languages. This allows researchers to share and reuse ontologies, while retaining the computational benefits of specialized implementations. We discuss how the translation approach to portability addresses several technical problems. One problem is how to accommodate the stylistic and organizational differences among representations while preserving declarative content. Another is how to translate from a very expressive language into restricted languages, remaining system-independent while preserving the computational efficiency of implemented systems. We describe how these problems are addressed by basing Ontolingua itself on an ontology of domain-independent, representational idioms.
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paper_title: COnto-Diff: generation of complex evolution mappings for life science ontologies

paper_content:

Life science ontologies evolve frequently to meet new requirements or to better reflect the current domain knowledge. The development and adaptation of large and complex ontologies is typically performed collaboratively by several curators. To effectively manage the evolution of ontologies it is essential to identify the difference (Diff) between ontology versions. Such a Diff supports the synchronization of changes in collaborative curation, the adaptation of dependent data such as annotations, and ontology version management. We propose a novel approach COnto-Diff to determine an expressive and invertible diff evolution mapping between given versions of an ontology. Our approach first matches the ontology versions and determines an initial evolution mapping consisting of basic change operations (insert/update/delete). To semantically enrich the evolution mapping we adopt a rule-based approach to transform the basic change operations into a smaller set of more complex change operations, such as merge, split, or changes of entire subgraphs. The proposed algorithm is customizable in different ways to meet the requirements of diverse ontologies and application scenarios. We evaluate the proposed approach for large life science ontologies including the Gene Ontology and the NCI Thesaurus and compare it with PromptDiff. We further show how the Diff results can be used for version management and annotation migration in collaborative curation.
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paper_title: Semi-automatic Integration of Learned Ontologies into a Collaborative Framework ⋆

paper_content:

The paper presents a novel ontology lifecycle scenario that ::: explicitly takes the dynamics and data-intensiveness of real ::: world applications into account. Changing and growing knowledge ::: is handled by semi-automatic incorporation of ontology learning ::: results into a collaborative ontology development framework. ::: This integration bases mainly on automatic negotiation of ::: agreed alignments, inconsistency resolution, an ontology ::: versioning system and support of natural language generation ::: tools, which alleviate the end-user effort in the incorporation ::: of new knowledge. The architecture of the respective framework ::: and notes on its progressive implementation are presented.
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paper_title: A multi-agent system for building dynamic ontologies

paper_content:

Ontologies building from text is still a time-consuming task which justifies the growth of Ontology Learning. Our system named Dynamo is designed along this domain but following an original approach based on an adaptive multi-agent architecture. In this paper we present a distributed hierarchical clustering algorithm, core of our approach. It is evaluated and compared to a more conventional centralized algorithm. We also present how it has been improved using a multi-criteria approach. With those results in mind, we discuss the limits of our system and add as perspectives the modifications required to reach a complete ontology building solution.
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paper_title: Winnowing Ontologies Based on Application Use

paper_content:

The requirements of specific applications and services are often over estimated when ontologies are reused or built. This sometimes results in many ontologies being too large for their intended purposes. It is not uncommon that when applications and services are deployed over an ontology, only a few parts of the ontology are queried and used. Identifying which parts of an ontology are being used could be helpful to winnow the ontology, i.e., simplify or shrink the ontology to smaller, more fit for purpose size. Some approaches to handle this problem have already been suggested in the literature. However, none of that work showed how ontology-based applications can be used in the ontology-resizing process, or how they might be affected by it. This paper presents a study on the use of the AKT Reference Ontology by a number of applications and services, and investigates the possibility of relying on this usage information to winnow that ontology.
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paper_title: Graph-based Discovery of Ontology Change Patterns

paper_content:

Ontologies can support a variety of purposes, ranging from capturing conceptual knowledge to the organisation of digital content and information. However, information systems are always subject to change and ontology change management can pose challenges. We investigate ontology change representation and discovery of change patterns. ::: Ontology changes are formalised as graph-based change logs. We use attributed graphs, which are typed over a generic graph with node and edge attribution.We analyse ontology change logs, represented as graphs, and identify frequent change sequences. Such sequences are applied as a reference in order to discover reusable, often domain-specific and usagedriven change patterns. We describe the pattern discovery algorithms and measure their performance using experimental results
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paper_title: Graph-based Discovery of Ontology Change Patterns

paper_content:

Ontologies can support a variety of purposes, ranging from capturing conceptual knowledge to the organisation of digital content and information. However, information systems are always subject to change and ontology change management can pose challenges. We investigate ontology change representation and discovery of change patterns. ::: Ontology changes are formalised as graph-based change logs. We use attributed graphs, which are typed over a generic graph with node and edge attribution.We analyse ontology change logs, represented as graphs, and identify frequent change sequences. Such sequences are applied as a reference in order to discover reusable, often domain-specific and usagedriven change patterns. We describe the pattern discovery algorithms and measure their performance using experimental results
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paper_title: WordNet: An Electronic Lexical Database

paper_content:

A teaching device to acquaint dental students and also patients with endodontic root canal techniques performed by dentists and utilizing an electronic oscillator having a scale reading in electric current measurement and a pair of electrical circuit conductors being connected at one end to the terminals of the oscillator and the opposite ends thereof respectively being connectable to one or more small diameter metal wires which simulate dental reamers and files which are movable in root canal-simulating passages of uniform diameter complementary to that of said wires and formed in a transparent model of a human tooth including a root and cusp thereon and mounted in a transparent enclosure in which the root portion of the tooth extends with the cusp of the model extending above the upper end of the enclosure.
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paper_title: An Adapted Lesk Algorithm for Word Sense Disambiguation Using WordNet

paper_content:

This paper presents an adaptation of Lesk's dictionary-based word sense disambiguation algorithm. Rather than using a standard dictionary as the source of glosses for our approach, the lexical database WordNet is employed. This provides a rich hierarchy of semantic relations that our algorithm can exploit. This method is evaluated using the English lexical sample data from the SENSEVAL-2 word sense disambiguation exercise, and attains an overall accuracy of 32%. This represents a significant improvement over the 16% and 23% accuracy attained by variations of the Lesk algorithm used as benchmarks during the Senseval-2 comparative exercise among word sense disambiguation systems.
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paper_title: A WordNet-based Algorithm for Word Sense Disambiguation

paper_content:

We present an algorithm for automatic word sense disambiguation based on lexical knowledge contained in WordNet and on the results of surface-syntactic analysis The algorithm is part of a system that analyzes texts in order to acquire knowledge in the presence of as little pre-coded semantic knowledge as possible On the other hand, we want to make the besl use of public-domain information sources such as WordNet Rather than depend on large amounts of hand-crafted knowledge or statistical data from large corpora, we use syntactic information and information in WordNet and minimize the need for other knowledge sources in the word sense disambiguation process We propose to guide disambiguation by semantic similarity between words and heuristic rules based on this similarity The algorithm has been applied to the Canadian Income Tax Guide Test results indicate that even on a relatively small text the proposed method produces correct noun meaning more than 72% of the time.
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paper_title: Semantically enriching folksonomies with FLOR

paper_content:

While the increasing popularity of folksonomies has lead to a vast quantity of tagged data, resource retrieval in these systems is limited by them being agnostic to the meaning (i.e., semantics) of tags. Our goal is to automatically enrich folksonomy tags (and implicitly the related resources) with formal semantics by associating them to relevant concepts defined in online ontologies. We introduce FLOR, a mechanism for automatic folksonomy enrichment by combining knowledge from WordNet and online ontologies.We experimentally tested FLOR on tag sets drawn ::: from 226 Flickr photos and obtained a precision value of 93% and an approximate recall of 49%.
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paper_title: Large scale integration of senses for the semantic web

paper_content:

Nowadays, the increasing amount of semantic data available on the Web leads to a new stage in the potential of Semantic Web applications. However, it also introduces new issues due to the heterogeneity of the available semantic resources. One of the most remarkable is redundancy, that is, the excess of different semantic descriptions, coming from different sources, to describe the same intended meaning. In this paper, we propose a technique to perform a large scale integration of senses (expressed as ontology terms), in order to cluster the most similar ones, when indexing large amounts of online semantic information. It can dramatically reduce the redundancy problem on the current Semantic Web. In order to make this objective feasible, we have studied the adaptability and scalability of our previous work on sense integration, to be translated to the much larger scenario of the Semantic Web. Our evaluation shows a good behaviour of these techniques when used in large scale experiments, then making feasible the proposed approach.
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paper_title: Sindice.com: A document-oriented lookup index for open linked data

paper_content:

Data discovery on the Semantic Web requires crawling and indexing of statements, in addition to the 'linked-data' approach of de-referencing resource URIs. Existing Semantic Web search engines are focused on database-like functionality, compromising on index size, query performance and live updates. We present Sindice, a lookup index over Semantic Web resources. Our index allows applications to automatically locate documents containing information about a given resource. In addition, we allow resource retrieval through inverse-functional properties, offer a full-text search and index SPARQL endpoints. Finally, we extend the sitemap protocol to efficiently index large datasets with minimal impact on data providers.
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paper_title: Using Ontological Contexts to Assess the Relevance of Statements in Ontology Evolution

paper_content:

Ontology evolution tools often propose new ontological changes in the form of statements. While different methods exist to check the quality of such statements to be added to the ontology (e.g., in terms of consistency and impact), their relevance is usually left to the user to assess. Relevance in this context is a notion of how well the statement fits in the target ontology. We present an approach to automatically assess such relevance. It is acknowledged in cognitive science and other research areas that a piece of information flowing between two entities is relevant if there is an agreement on the context used between the entities. In our approach, we derive the context of a statement from online ontologies in which it is used, and study how this context matches with the target ontology. We identify relevance patterns that give an indication of relevance when the statement context and the target ontology fulfill specific conditions. We validate our approach through an experiment in three different domains, and show how our pattern-based technique outperforms a naive overlap-based approach.
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paper_title: Bridging the gap between OWL and relational databases

paper_content:

Schema statements in OWL are interpreted quite differently from analogous statements in relational databases. If these statements are meant to be interpreted as integrity constraints (ICs), OWL's interpretation may seem confusing and/or inappropriate. Therefore, we propose an extension of OWL with ICs that captures the intuition behind ICs in relational databases. We discuss the algorithms for checking IC satisfaction for different types of knowledge bases, and show that, if the constraints are satisfied, we can disregard them while answering a broad range of positive queries.
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paper_title: The knowledge model of Protege-2000: combining interoperability and flexibility

paper_content:

Knowledge-based systems have become ubiquitous in recent years. Knowledge-base developers need to be able to share and reuse knowledge bases that they build. Therefore, interoperability among different knowledge-representation systems is essential. The Open Knowledge-Base Connectivity protocol (OKBC) is a common query and construction interface for frame-based systems that facilitates this interoperability. ProtEgE-2000 is an OKBC-compatible knowledge-base-editing environment developed in our laboratory. We describe ProtEgE-2000 knowledge model that makes the import and export of knowledge bases from and to other knowledge-base servers easy. We discuss how the requirements of being a usable and configurable knowledge-acquisition tool affected our decisions in the knowledge-model design. ProtEgE-2000 also has a flexible metaclass architecture which provides configurable templates for new classes in the knowledge base. The use of metaclasses makes ProtEgE-2000 easily extensible and enables its use with other knowledge models. We demonstrate that we can resolve many of the differences between the knowledge models of ProtEgE-2000 and Resource Description Framework (RDF)--a system for annotating Web pages with knowledge elements--by defining a new metaclass set. Resolving the differences between the knowledge models in declarative way enables easy adaptation of ProtEgE-2000 as an editor for other knowledge-representation systems.
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paper_title: EvoPat - pattern-based evolution and refactoring of RDF knowledge bases

paper_content:

Facilitating the seamless evolution of RDF knowledge bases on the Semantic Web presents still a major challenge. In this work we devise EvoPat - a pattern-based approach for the evolution and refactoring of knowledge bases. The approach is based on the definition of basic evolution patterns, which are represented declaratively and can capture simple evolution and refactoring operations on both data and schema levels. For more advanced and domain-specific evolution and refactorings, several simple evolution patterns can be combined into a compound one. We performed a comprehensive survey of possible evolution patterns with a combinatorial analysis of all possible before/after combinations, resulting in an extensive catalog of usable evolution patterns. Our approach was implemented as an extension for the OntoWiki semantic collaboration platform and framework.
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paper_title: Ontology change: classification and survey

paper_content:

Ontologies play a key role in the advent of the Semantic Web. An important problem when dealing with ontologies is the modification of an existing ontology in response to a certain need for change. This problem is a complex and multifaceted one, because it can take several different forms and includes several related subproblems, like heterogeneity resolution or keeping track of ontology versions. As a result, it is being addressed by several different, but closely related and often overlapping research disciplines. Unfortunately, the boundaries of each such discipline are not clear, as the same term is often used with different meanings in the relevant literature, creating a certain amount of confusion. The purpose of this paper is to identify the exact relationships between these research areas and to determine the boundaries of each field, by performing a broad review of the relevant literature.
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paper_title: Toward Updates in Description Logics

paper_content:

The use of DL systems to add reasoning capabilities to database is now a major trend in convergence between knowledge base and database system but is still confronted with the issue of data update. DL systems provide fact additions and retractions but no real object update mechanisms. We present a semantics for update that favours attribute values to concept membership and deals with incomplete information. After relating our work to an existing previous one on update semantics we address implementation issues.
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paper_title: A Framework for Ontology Evolution in Collaborative Environments

paper_content:

With the wider use of ontologies in the Semantic Web and as part of production systems, multiple scenarios for ontology maintenance and evolution are emerging. For example, successive ontology versions can be posted on the (Semantic) Web, with users discovering the new versions serendipitously; ontology-development in a collaborative environment can be synchronous or asynchronous; managers of projects may exercise quality control, examining changes from previous baseline versions and accepting or rejecting them before a new baseline is published, and so on. In this paper, we present different scenarios for ontology maintenance and evolution that we have encountered in our own projects and in those of our collaborators. We define several features that categorize these scenarios. For each scenario, we discuss the high-level tasks that an editing environment must support. We then present a unified comprehensive set of tools to support different scenarios in a single framework, allowing users to switch between different modes easily.
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paper_title: A Formal Approach for RDF/S Ontology Evolution

paper_content:

In this paper, we consider the problem of ontology evolution in the face of a change operation. We devise a general-purpose algorithm for determining the effects and side-effects of a requested elementary or complex change operation. Our work is inspired by belief revision principles (i.e., validity, success and minimal change) and allows us to handle any change operation in a provably rational and consistent manner. To the best of our knowledge, this is the first approach overcoming the limitations of existing solutions, which deal with each change operation on a per-case basis. Additionally, we rely on our general change handling algorithm to implement specialized versions of it, one per desired change operation, in order to compute the equivalent set of effects and side-effects. This work was partially supported by the EU projects CASPAR (FP6-2005-IST-033572) and KP-LAB (FP6-2004-IST-27490).
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paper_title: ON THE LOGIC OF THEORY CHANGE: PARTIAL MEET CONTRACTION AND REVISION FUNCTIONS

paper_content:

This paper extends earlier work by its authors on formal aspects of the processes of contracting a theory to eliminate a proposition and revising a theory to introduce a proposition. In the course of the earlier work, Gardenfors developed general postulates of a more or less equational nature for such processes, whilst Alchourron and Makinson studied the particular case of contraction functions that are maximal, in the sense of yielding a maximal subset of the theory (or alternatively, of one of its axiomatic bases), that fails to imply the proposition being eliminated. In the present paper, the authors study a broader class, including contraction functions that may be less than maximal. Specifically, they investigate “partial meet contraction functions”, which are defined to yield the intersection of some nonempty family of maximal subsets of the theory that fail to imply the proposition being eliminated. Basic properties of these functions are established: it is shown in particular that they satisfy the Gardenfors postulates, and moreover that they are sufficiently general to provide a representation theorem for those postulates. Some special classes of partial meet contraction functions, notably those that are “relational” and “transitively relational”, are studied in detail, and their connections with certain “supplementary postulates” of Gardenfors investigated, with a further representation theorem established.
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paper_title: Extending OWL with Integrity Constraints

paper_content:

Since m1 and m2 are not explicitly defined to be different from each other, they will be inferred to be same due to the cardinality restriction. However, in many cases, the reason to use functional properties is not to draw this inference, but to detect an inconsistency. When the information about instances are coming from multiple sources we cannot always assume explicit inequalities will be present. In these scenarios, there is a strong need to use OWL as an Integrity Constraint (IC) language with closed world semantics. That is, we would like to adopt the OWA without the UNA for parts of the domain where we have incomplete
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paper_title: RUL : A Declarative Update Language for RDF

paper_content:

We propose a declarative update language for RDF graphs which is based on the paradigms of query and view languages RQL and RVL. Our language, called RUL, ensures that the execution of the update primitives on nodes and arcs neither violates the semantics of the RDF model nor the semantics of the given RDFS schema. In addition, RUL supports fine-grained updates at the class and property instance level, set-oriented updates with a deterministic semantics and takes benefit of the full expressive power of RQL for restricting the range of variables to nodes and arcs of RDF graphs.
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paper_title: SPARQLing constraints for RDF

paper_content:

The goal of the Semantic Web is to support semantic interoperability between applications exchanging data on the web. The idea heavily relies on data being made available in machine readable format, using semantic markup languages. In this regard, the W3C has standardized RDF as the basic markup language for the Semantic Web. In contrast to relational databases, where data relationships are implicitly given by schema information as well as primary and foreign key constraints, relationships in semantic markup languages are made explicit. When mapping relational data into RDF, it is desirable to maintain the information implied by the origin constraints. As an improvement over existing approaches, our scheme allows for translating conventional databases into RDF without losing general constraints and vital key information. As much as in the relational model, those information are indispensable for data consistency and, as shown by example, can serve as a basis for semantic query optimization. We underline the practicability of our approach by showing that SPARQL, the most popular query language for RDF, can be used as a constraint language, akin to SQL in the relational context. As a theoretical contribution, we also discuss satisfiability for interesting classes of constraints and combinations thereof.
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paper_title: OntoEdit: Multifaceted Inferencing for Ontology Engineering

paper_content:

Ontologies now play an important role for many knowledge-intensive applications for which they provide a source of precisely defined terms. The terms are used for concise communication across people and applications. Tools such as ontology editors facilitate the creation and maintenance of ontologies. OntoEdit is an ontology editor that has been developed keeping five main objectives in mind: 1. Ease of use. 2. Methodology-guided development of ontologies. 3. Ontology development with help of inferencing. 4. Development of ontology axioms. 5. Extensibility through plug-in structure.
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paper_title: Updating Description Logic ABoxes

paper_content:

Description logic (DL) ABoxes are a tool for describing the state of affairs in an application domain. In this paper, we consider the problem of updating ABoxes when the state changes. We assume that changes are described at an atomic level, i.e., in terms of possibly negated ABox assertions that involve only atomic concepts and roles. We analyze such basic ABox updates in several standard DLs by investigating whether the updated ABox can be expressed in these DLs and, if so, whether it is computable and what is its size. It turns out that DLs have to include nominals and the "@" constructor of hybrid logic (or, equivalently, admit Boolean ABoxes) for updated ABoxes to be expressible. We devise algorithms to compute updated ABoxes in several expressive DLs and show that an exponential blowup in the size of the whole input (original ABox + update information) cannot be avoided unless every PTIME problem is LOGTIME-parallelizable. We also exhibit ways to avoid an exponential blowup in the size of the original ABox, which is usually large compared to the update information.
---
paper_title: A Theoretical Model to Handle Ontology Debugging & Change Through Argumentation

paper_content:

A miniature optical source which includes at least one thin film of active laser materials having, in addition, non-linear properties. A pump laser for emitting a beam of a wavelength allowing for the pumping of the thin film of active laser material perpendicularly to the plane of the thin film. Also, an optical cavity constituted by two mirrors whose coefficients of reflection are maximum at the laser wavelength of the active laser material is further provided. The miniature optical source may find particular application in a physically compact laser emitting in the visible spectrum.
---
paper_title: Formal foundations for RDF/S KB evolution

paper_content:

There are ongoing efforts to provide declarative formalisms of integrity constraints over RDF/S data. In this context, addressing the evolution of RDF/S knowledge bases while respecting associated constraints is a challenging issue, yet to receive a formal treatment. We provide a theoretical framework for dealing with both schema and data change requests. We define the notion of a rational change operator as one that satisfies the belief revision principles of Success, Validity and Minimal Change. The semantics of such an operator are subject to customization, by tuning the properties that a rational change should adhere to. We prove some interesting theoretical results and propose a general-purpose algorithm for implementing rational change operators in knowledge bases with integrity constraints, which allows us to handle uniformly any possible change request in a provably rational and consistent manner. Then, we apply our framework to a well-studied RDF/S variant, for which we suggest a specific notion of minimality. For efficiency purposes, we also describe specialized versions of the general evolution algorithm for the RDF/S case, which provably have the same semantics as the general-purpose one for a limited set of (useful in practice) types of change requests.
---
paper_title: Containment and minimization of RDF/S query patterns

paper_content:

Semantic query optimization (SQO) has been proved to be quite useful in various applications (e.g., data integration, graphical query generators, caching, etc.) and has been extensively studied for relational, deductive, object, and XML databases. However, less attention to SQO has been devoted in the context of the Semantic Web. In this paper, we present sound and complete algorithms for the containment and minimization of RDF/S query patterns. More precisely, we consider two widely used RDF/S query fragments supporting pattern matching at the data, but also, at the schema level. To this end, we advocate a logic framework for capturing the RDF/S data model and semantics and we employ well-established techniques proposed in the relational context, in particular, the Chase and Backchase algorithms.
---
paper_title: Change Management for Metadata Evolution

paper_content:

In order to meet the demands of the Semantic Web, today’s ontologies need to be dynamic, networked structures. One important challenge, therefore, is to develop an integrated approach to the evolution process of ontologies and related metadata. Within this context, the specific goal of this work is to capture the evolution of metadata due to changed concepts, relations or metadata in one of the ontologies, and to capture changes to the ontology caused by changes to the metadata. After a short discussion of the nature of metadata, we propose a methodology to capture (1) the evolution of metadata induced by changes to the ontologies, and (2) the evolution of the ontology induced by changes to the underlying metadata. This will lead to the implementation of an approach for evolution of metadata related to ontologies.
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paper_title: Belief contraction without recovery

paper_content:

The postulate of recovery is commonly regarded to be the intuitively least compelling of the six basic Gärdenfors postulates for belief contraction. We replace recovery by the seemingly much weaker postulate of core-retainment, which ensures that if x is excluded from K when p is contracted, then x plays some role for the fact that K implies p. Surprisingly enough, core-retainment together with four of the other Gärdenfors postulates implies recovery for logically closed belief sets. Reasonable contraction operators without recovery do not seem to be possible for such sets. Instead, however, they can be obtained for non-closed belief bases. Some results on partial meet contractions on belief bases are given, including an axiomatic characterization and a non-vacuous extension of the AGM closure condition.
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paper_title: Model-based Revision Operators for Terminologies in Description Logics

paper_content:

The problem of revising an ontology consistently is closely related to the problem of belief revision which has been widely discussed in the literature. Some syntax-based belief revision operators have been adapted to revise ontologies in Description Logics (DLs). However, these operators remove the whole axioms to resolve logical contradictions and thus are not fine-grained. In this paper, we propose three model-based revision operators to revise terminologies in DLs. We show that one of them is more rational than others by comparing their logical properties. Therefore, we focus on this revision operator. We also consider the problem of computing the result of revision by our operator with the help of the notion of concept forgetting. Finally, we analyze the computational complexity of our revision operator.
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paper_title: Generalizing the AGM postulates: preliminary results and applications

paper_content:

One of the crucial actions any reasoning system must undertake is the updating of its Knowledge Base (KB). This problem is usually referred to as the problem of belief change. The AGM approach, introduced in (Alchourron, Gardenfors, and Makinson 1985), is the dominating paradigm in the area but it makes some non-elementary assumptions about the logic at hand which disallow its direct application in some classes of logics. In this paper, we drop all such assumptions and determine the necessary and sufficient conditions for a logic to support AGMcompliant operators. Our approach is directly applicable to a much broader class of logics. We apply our results to establish connections between the problem of updating in Description Logics (DLs) and the AGM postulates. Finally, we investigate why belief base operators cannot satisfy the AGM postulates in standard logics.
---
paper_title: R.: On instance-level update and erasure in description logic ontologies

paper_content:

A Description Logic (DL) ontology is constituted by two components, a TBox that expresses general knowledge about the concepts and their relationships, and an ABox that describes the properties of individuals that are instances of concepts. We address the problem of how to deal with changes to a DL ontology, when these changes affect only the ABox, i.e. when the TBox is considered invariant. We consider two basic changes, namely instance-level update and instance-level erasure, roughly corresponding to the addition and the deletion of a set of facts involving individuals. We characterize the semantics of instance-level update and erasure on the basis of the approaches proposed by Winslett and by Katsuno and Mendelzon. Interestingly, DLs are typically not closed with respect to instance-level update and erasure, in the sense that the set of models corresponding to the application of any of these operations to a knowledge base in a DL L may not be expressible by ABoxes in L. In particular, we show that this is true for DL-LiteF, a tractable DL that is oriented towards data-intensive applications. To deal with this problem, we first introduce DL-LiteFS, a DL that minimally extends DL-LiteF and is closed with respect to instance-level update, and present a polynomial algorithm for computing instance-level update in this logic. Then, we provide a principled notion of best approximation with respect to a fixed language L of instance-level update and erasure, and exploit the algorithm for instance-level update for DL-LiteFS to get polynomial algorithms for approximated instance-level update and erasure for DL-LiteF. These results confirm the nice computational properties of DL-LiteF for data intensive applications, even where information about instances is not only read, but also written.
---
paper_title: ON THE LOGIC OF THEORY CHANGE: PARTIAL MEET CONTRACTION AND REVISION FUNCTIONS

paper_content:

This paper extends earlier work by its authors on formal aspects of the processes of contracting a theory to eliminate a proposition and revising a theory to introduce a proposition. In the course of the earlier work, Gardenfors developed general postulates of a more or less equational nature for such processes, whilst Alchourron and Makinson studied the particular case of contraction functions that are maximal, in the sense of yielding a maximal subset of the theory (or alternatively, of one of its axiomatic bases), that fails to imply the proposition being eliminated. In the present paper, the authors study a broader class, including contraction functions that may be less than maximal. Specifically, they investigate “partial meet contraction functions”, which are defined to yield the intersection of some nonempty family of maximal subsets of the theory that fail to imply the proposition being eliminated. Basic properties of these functions are established: it is shown in particular that they satisfy the Gardenfors postulates, and moreover that they are sufficiently general to provide a representation theorem for those postulates. Some special classes of partial meet contraction functions, notably those that are “relational” and “transitively relational”, are studied in detail, and their connections with certain “supplementary postulates” of Gardenfors investigated, with a further representation theorem established.
---
paper_title: First Steps Towards Revising Ontologies

paper_content:

When modeling an ontology, one very often wants to add new information and keep the resulting ontology consistent. Belief Revision deals with the problem of consistently adding new formulas to a knowledge base. In this paper, we present some steps towards applying belief revision methods to ontologies based on description logics. We depart from the well known AGM-paradigm and show how it can be adapted in order to be applied to description logics.
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paper_title: Weakening conflicting information for iterated revision and knowledge integration

paper_content:

The ability to handle exceptions, to perform iterated belief revision and to integrate information from multiple sources is essential for a commonsense reasoning agent. These important skills are related in the sense that they all rely on resolving inconsistent information. In this paper we develop a novel and useful strategy for conflict resolution, and compare and contrast it with existing strategies. Ideally the process of conflict resolution should conform with the principle of Minimal Change and should result in the minimal loss of information. Our approach to minimizing the loss of information is to weaken information involved in conflicts rather than completely discarding it. We implemented and tested the relative performance of our new strategy in three different ways. Surprisingly, we are able to demonstrate that it provides a computationally effective compilation of the lexicographical strategy; a strategy which is known to have desirable theoretical properties.
---
paper_title: A new approach to knowledge base revision in DL-lite

paper_content:

Revising knowledge bases (KBs) in description logics (DLs) in a syntax-independent manner is an important, nontrivial problem for the ontology management and DL communities. Several attempts have been made to adapt classical model-based belief revision and update techniques to DLs, but they are restricted in several ways. In particular, they do not provide operators or algorithms for general DL KB revision. The key difficulty is that, unlike propositional logic, a DL KB may have infinitely many models with complex (and possibly infinite) structures, making it difficult to define and compute revisions in terms of models. In this paper, we study general KBs in a specific DL in the DL-Lite family. We introduce the concept of features for such KBs, develop an alternative semantic characterization of KBs using features (instead of models), define two specific revision operators for KBs, and present the first algorithm for computing best approximations for syntax-independent revisions of KBs.
---
paper_title: The Meaning of Erasing in RDF under the Katsuno-Mendelzon Approach

paper_content:

The basic data model for the Semantic Web is RDF. In this paper we address updates in RDF. It is known that the semantics of updates for data models becomes unclear when the model turns, even slightly, more general than a simple relational structure. Using the framework of KatsunoMendelzon, we define a semantics for updates in RDF. Particularly we explore the behavior of this semantics for the “erase” operator (which in general is not expressible in RDF). Our results include a proposal of sound semantics for RDF updates, a characterization of the maximal RDF graph which captures exactly all consequences of the erase operation expressible in RDF, and complexity results about the computation of this graph and updates in RDF in general.
---
paper_title: A classification of ontology modification

paper_content:

Recent research in ontologies and descriptions logics has focused on compromising between expressiveness and reasoning ability, with many other issues being neglected One major issue that has been neglected is how one should go about in modifying ontologies as inconsistency arises The central concern of this problem is therefore to determine the most rational way of modifying ontologies, such that no extra knowledge would be retained in or retracted from the knowledge base The purpose of this paper is to outline the complexities in this and to present some insights into the problem of ontology modification Description logic (DL) is used in this paper as the underlying logic for the representation of ontology, and ontology modification is performed based on this logic.
---
paper_title: On Applying the AGM Theory to DLs and OWL

paper_content:

It is generally acknowledged that any Knowledge Base (KB) should be able to adapt itself to new information received. This problem has been extensively studied in the field of belief change, the dominating approach being the AGM theory. This theory set the standard for determining the rationality of a given belief change mechanism but was placed in a certain context which makes it inapplicable to logics used in the Semantic Web, such as Description Logics (DLs) and OWL. We believe the Semantic Web community would benefit from the application of the AGM theory to such logics. This paper is a preliminary study towards the feasibility of this application. Our approach raises interesting theoretical challenges and has an important practical impact too, given the central role that DLs and OWL play in the Semantic Web.
---
paper_title: Knowledge base revision in description logics

paper_content:

Ontology evolution is an important problem in the Semantic Web research. Recently, Alchourron, Gardenfors and Markinson's (AGM) theory on belief change has been applied to deal with this problem. However, most of current work only focuses on the feasibility of the application of AGM postulates on contraction to description logics (DLs), a family of ontology languages. So the explicit construction of a revision operator is ignored. In this paper, we first generalize the AGM postulates on revision to DLs. We then define two revision operators in DLs. One is the weakening-based revision operator which is defined by weakening of statements in a DL knowledge base and the other is its refinement. We show that both operators capture some notions of minimal change and satisfy the generalized AGM postulates for revision.
---
paper_title: A First Step Towards Stream Reasoning

paper_content:

While reasoners are year after year scaling up in the classical, time invariant domain of ontological knowledge, reasoning upon rapidly changing information has been neglected or forgotten. On the contrary, processing of data streams has been largely investigated and specialized Stream Database Management Systems exist. In this paper, by coupling reasoners with powerful, reactive, throughput-efficient stream management systems, we introduce the concept of Stream Reasoning. We expect future realization of such concept to have high impact on the future Internet because it enables reasoning in real time, at a throughput and with a reactivity not obtained in previous works.
---
paper_title: HECATAEUS: Regulating schema evolution

paper_content:

HECATAEUS is an open-source software tool for enabling impact prediction, what-if analysis, and regulation of relational database schema evolution. We follow a graph theoretic approach and represent database schemas and database constructs, like queries and views, as graphs. Our tool enables the user to create hypothetical evolution events and examine their impact over the overall graph before these are actually enforced on it. It also allows definition of rules for regulating the impact of evolution via (a) default values for all the nodes of the graph and (b) simple annotations for nodes deviating from the default behavior. Finally, HECATAEUS includes a metric suite for evaluating the impact of evolution events and detecting crucial and vulnerable parts of the system.
---
paper_title: Ontology evolution in data integration: query rewriting to the rescue

paper_content:

The evolution of ontologies is an undisputed necessity in ontologybased data integration. In such systems ontologies are used as global schema in order to formulate queries that are answered by the data integration systems. Yet, few research efforts have focused on addressing the need to reflect ontology evolution onto the underlying data integration systems. In most of these systems, when ontologies change their relations with the data sources, i.e., the mappings, are recreated manually, a process which is known to be error-prone and timeconsuming. In this paper, we provide a solution that allows query answering under evolving ontologies without mapping redefinition. To achieve that, query rewriting techniques are exploited in order to produce equivalent rewritings among ontology versions. Whenever equivalent rewritings cannot be produced we a) guide query redefinition or b) provide the best "over-approximations". We show that our approach can greatly reduce human effort spent since continuous mapping redefinition on evolving ontologies is no longer necessary.
---
paper_title: Optimising ontology stream reasoning with truth maintenance system

paper_content:

So far researchers in the Description Logics / Ontology communities mainly consider ontology reasoning services for static ontologies. The rapid development of the Semantic Web and its emerging data ask for reasoning technologies for dynamic knowledge streams. Existing work on stream reasoning is focused on lightweight languages such as RDF and RDFS. In this paper, we introduce the notion of Ontology Stream Management System (OSMS) and present a stream-reasoning approach based on Truth Maintenance System (TMS). We present optimised EL++ algorithm to reduce memory consumption. Our evaluations show that the optimisation improves TMS-enabled EL++ reasoning to deal with relatively large volumes of data and update efficiently.
---
paper_title: Y.: Policy-regulated Management of ETL Evolution

paper_content:

In this paper, we discuss the problem of performing impact prediction for changes that occur in the schema/structure of the data warehouse sources. We abstract Extract-Transform-Load (ETL) activities as queries and sequences of views. ETL activities and its sources are uniformly modeled as a graph that is annotated with policies for the management of evolution events. Given a change at an element of the graph, our method detects the parts of the graph that are affected by this change and highlights the way they are tuned to respond to it. For many cases of ETL source evolution, we present rules so that both syntactical and semantic correctness of activities are retained. Finally, we experiment with the evaluation of our approach over real-world ETL workflows used in the Greek public sector.
---
paper_title: C-SPARQL: SPARQL for continuous querying

paper_content:

C-SPARQL is an extension of SPARQL to support continuous queries, registered and continuously executed over RDF data streams, considering windows of such streams. Supporting streams in RDF format guarantees interoperability and opens up important applications, in which reasoners can deal with knowledge that evolves over time. We present C-SPARQL by means of examples in Urban Computing.
---
paper_title: Changing Ontology Breaks Queries

paper_content:

Updating an ontology that is in use may result in inconsistencies between the ontology and the knowledge base, dependent ontologies and applications/services. Current research concentrates on the creation of ontologies and how to manage ontology changes in terms of mapping ontology versions and keeping consistent with the instances. Very little work investigated controlling the impact on dependent applications/services; which is the aim of the system presented in this paper. The approach we propose is to make use of ontology change logs to analyse incoming RDQL queries and amend them as necessary. Revised queries can then be used to query the ontology and knowledge base as requested by the applications and services. We describe our prototype system and discuss related problems and future directions.
---
paper_title: Enabling Active Ontology Change Management within Semantic Web-based Applications

paper_content:

Enabling traceable ontology changes is becoming a critical issue for ontology-based applications. Updating an ontology that is in use may result in inconsistencies between the ontology and the knowledge base, dependent ontologies and applications/services. Current research concentrates on the creation of ontologies and how to manage ontology changes in terms of mapping ontology versions and keeping consistent with the instances. Very little work investigated on-the-fly keeping track of ontology changes while update (active ontology versioning) and using these information to control the impact on dependent applications/services, which is the aim of our research presented in this thesis. The approach we propose is to make use of ontology change logs as a check-point to analyse changed entities related to the requested services via end-user’s incoming queries (RDQL/SPARQL) and amend them as necessary to maintain the validation and continuousness of the dependent application. Firstly, We build up Log Ontology I as the concept structure to organize and construct the change information, develop our prototype system to demonstrate how the change information retrieved from Log Ontology I could be used to control the impacts brought by the ontology changes on the dependent applications and services. And then, by analysing the limitations and difficulties of our prototype system in maintaining the services related to the more complex ontology changes, we identify that the problem which fails the system facing the more complex ontology changes is the inabilities of Log Ontology I to represent complex change information in a semantic fashion. Therefore, we retract to put more focuses on Log Ontology I to enable the implementation of the mechanism to on-the-fly keep track of ontology change information, forming Log Ontology II, in order to reserve the semantics of ontology change from the beginning of ontology update process. Finally we discuss the future direction in terms of how the improved Log Ontology II enables the better service validation and continuousness maintenance of changing-ontology-based applications.
---
paper_title: Evaluating the validity of data instances against ontology evolution over the Semantic Web

paper_content:

It is natural for ontologies to evolve over time. These changes could be at structural and semantic levels. Due to changes to an ontology, its data instances may become invalid, and as a result, may become non-interpretable. In this paper, we address precisely this problem, validity of data instances due to ontological evolution. Towards this end, we make the following three novel contributions to the area of Semantic Web. First, we propose formal notions of structural validity and semantic validity of data instances, and then present approaches to ensure them. Second, we propose semantic view as part of an ontology, and demonstrate that it is sufficient to validate a data instance against the semantic view rather than the entire ontology. We discuss how the semantic view can be generated through an implication analysis, i.e., how semantic changes to one component imply semantic changes to other components in the ontology. Third, we propose a validity identification approach that employs locally maintaining a hash value of the semantic view at the data instance.
---
paper_title: Ontology evolution: assisting query migration

paper_content:

Information systems rely more and more on semantic web ontologies to share and interpret data within and across research domains. However, an important problem when dealing with ontologies is the fact that they are living artefacts and subject to change. When ontologies evolve, queries formulated using a past ontology version might become invalid and should be redefined or adapted. In this paper we propose a solution in order to identify the impact of ontology evolution on queries and to ease query migration. We present a module that receives as input the sequence of changes between the two ontology versions along with a set of queries and automatically identifies the specific change operations that affect the input queries. Besides the automatic identification of the affecting change operations, query migration is further aided by providing an explanation for the specific invalidation. This explanation is presented graphically by means of change paths that represent the evolution of the specific parts of the ontology that invalidate the query. We evaluate the time complexity of our approach and show how it can possibly reduce the human effort spent on query redefinition/adaptation.
---
paper_title: Ontology versioning on the Semantic Web

paper_content:

Ontologies are often seen as basic building blocks for the Semantic Web, as they provide a reusable piece of knowledge about a specific domain. However, those pieces of knowledge are not static, but evolve over time. Domain changes, adaptations to different tasks, or changes in the conceptualization require modifications of the ontology. The evolution of ontologies causes operability problems, which will hamper their effective reuse. A versioning mechanism might help to reduce those problems, as it will make the relations between different revisions of an ontology explicit. This paper will discuss the problem of ontology versioning. Inspired by the work done in database schema versioning and program interface versioning, it will also propose building blocks for the most important aspects of a versioning mechanism, i.e., ontology identification and change specification.
---
paper_title: Evolution Management for Interconnected Ontologies

paper_content:

Mappings between ontologies are easily harmed by changes in the ontologies. In this paper we explain a mechanism to define modular ontologies and mappings in a way that allows for local containment of terminological reasoning. We have also developed a change detection and analysis method that predicts the effect of changes on the concept hierarchy. This method determines whether the changes in one ontology affect the reasoning inside other ontologies or not. Together, these mechanisms allow ontologies to evolve without unpredictable effects on other ontologies. In this paper, we also apply these methods in a case study that is undertaken in a EU IST project.
---
paper_title: Analyzing the evolution of life science ontologies and mappings

paper_content:

Ontologies are heavily developed and used in life sciences and undergo continuous changes. However, the evolution of life science ontologies and references to them (e.g., annotations) is not well understood and has received little attention so far. We therefore propose a generic framework for analyzing both the evolution of ontologies and the evolution of ontology-related mappings, in particular annotations referring to ontologies and similarity (match) mappings between ontologies. We use our framework for an extensive comparative evaluation of evolution measures for 16 life science ontologies. Moreover, we analyze the evolution of annotation mappings and ontology mappings for the Gene Ontology.
---
paper_title: Ontology Evolution Issues in Adaptable Information Management Systems

paper_content:

Currently, ontology based information management systems have drawn great attentions. However, one of the challenges is how to manage the evolution of the ontology. If ontology evolution was not considered beforehand in the modeling phase of the system, then it may cause potential inconsistencies among the components of the ontology and the dependent applications. Besides the evolution of an ontology may interfere with the running of its dependent applications. Hence, in this paper the approaches of maintaining the consistency and keeping the continuousness of the dependent applications during the evolution are analyzed. Firstly, a virtual space based framework is put forward and most of the changes are to be made in the virtual space. Then two types of property changes are analyzed and solutions for processing them are given in detail. Besides, a register record approach is addressed for checking the dependency between the applications and the ontology schema.
---
paper_title: Exelixis: evolving ontology-based data integration system

paper_content:

The evolution of ontologies is an undisputed necessity in ontology-based data integration. Yet, few research efforts have focused on addressing the need to reflect ontology evolution onto the underlying data integration systems. We present Exelixis, a web platform that enables query answering over evolving ontologies without mapping redefinition. This is achieved by rewriting queries among ontology versions. First, changes between ontologies are automatically detected and described using a high level language of changes. Those changes are interpreted as sound global-as-view (GAV) mappings. Then query expansion is applied in order to consider constraints from the ontology and unfolding to apply the GAV mappings. Whenever equivalent rewritings cannot be produced we a) guide query redefinition and/or b) provide the best "over-approximations", i.e. the minimally-containing and minimally-generalized rewritings. For the demonstration we will use four versions of the CIDOC-CRM ontology and real user queries to show the functionality of the system. Then we will allow conference participants to directly interact with the system to test its capabilities.
---
paper_title: Automatic Support for Formative Ontology Evaluation

paper_content:

Just as testing is an integral part of software engineering, so is ontology evaluation an integral part of ontology engineering. We have implemented automated support for formative ontology evaluation based on the two principles of i) checking for compliance with modelling guidelines and ii) reviewing entailed statements in MoKi, a wiki based ontology engineering environment. These principles exist in state of the art literature and good ontology engineering and evaluation practice, but have not so far been widely integrated into ontology engineering tools.
---
paper_title: Consistent Evolution of OWL Ontologies

paper_content:

Support for ontology evolution is extremely important in ontology engineering and application of ontologies in dynamic environments. A core aspect in the evolution process is the to guarantee consistency of the ontology when changes occur. In this paper we discuss the consistent evolution of OWL ontologies. We present a model for the semantics of change for OWL ontologies, considering structural, logical, and user-defined consistency. We introduce resolution strategies to ensure that consistency is maintained as the ontology evolves.
---
paper_title: Automatic Support for Formative Ontology Evaluation

paper_content:

Just as testing is an integral part of software engineering, so is ontology evaluation an integral part of ontology engineering. We have implemented automated support for formative ontology evaluation based on the two principles of i) checking for compliance with modelling guidelines and ii) reviewing entailed statements in MoKi, a wiki based ontology engineering environment. These principles exist in state of the art literature and good ontology engineering and evaluation practice, but have not so far been widely integrated into ontology engineering tools.
---
paper_title: Consistent Evolution of OWL Ontologies

paper_content:

Support for ontology evolution is extremely important in ontology engineering and application of ontologies in dynamic environments. A core aspect in the evolution process is the to guarantee consistency of the ontology when changes occur. In this paper we discuss the consistent evolution of OWL ontologies. We present a model for the semantics of change for OWL ontologies, considering structural, logical, and user-defined consistency. We introduce resolution strategies to ensure that consistency is maintained as the ontology evolves.
---
paper_title: HECATAEUS: Regulating schema evolution

paper_content:

HECATAEUS is an open-source software tool for enabling impact prediction, what-if analysis, and regulation of relational database schema evolution. We follow a graph theoretic approach and represent database schemas and database constructs, like queries and views, as graphs. Our tool enables the user to create hypothetical evolution events and examine their impact over the overall graph before these are actually enforced on it. It also allows definition of rules for regulating the impact of evolution via (a) default values for all the nodes of the graph and (b) simple annotations for nodes deviating from the default behavior. Finally, HECATAEUS includes a metric suite for evaluating the impact of evolution events and detecting crucial and vulnerable parts of the system.
---
paper_title: Ontology evolution in data integration: query rewriting to the rescue

paper_content:

The evolution of ontologies is an undisputed necessity in ontologybased data integration. In such systems ontologies are used as global schema in order to formulate queries that are answered by the data integration systems. Yet, few research efforts have focused on addressing the need to reflect ontology evolution onto the underlying data integration systems. In most of these systems, when ontologies change their relations with the data sources, i.e., the mappings, are recreated manually, a process which is known to be error-prone and timeconsuming. In this paper, we provide a solution that allows query answering under evolving ontologies without mapping redefinition. To achieve that, query rewriting techniques are exploited in order to produce equivalent rewritings among ontology versions. Whenever equivalent rewritings cannot be produced we a) guide query redefinition or b) provide the best "over-approximations". We show that our approach can greatly reduce human effort spent since continuous mapping redefinition on evolving ontologies is no longer necessary.
---
paper_title: Y.: Policy-regulated Management of ETL Evolution

paper_content:

In this paper, we discuss the problem of performing impact prediction for changes that occur in the schema/structure of the data warehouse sources. We abstract Extract-Transform-Load (ETL) activities as queries and sequences of views. ETL activities and its sources are uniformly modeled as a graph that is annotated with policies for the management of evolution events. Given a change at an element of the graph, our method detects the parts of the graph that are affected by this change and highlights the way they are tuned to respond to it. For many cases of ETL source evolution, we present rules so that both syntactical and semantic correctness of activities are retained. Finally, we experiment with the evaluation of our approach over real-world ETL workflows used in the Greek public sector.
---
paper_title: Dynamic Change Evaluation for Ontology Evolution in the Semantic Web

paper_content:

Changes in an ontology may have a disruptive impact on any system using it. This impact may depend on structural changes such as introduction or removal of concept definitions, or it may be related to a change in the expected performance of the reasoning tasks. As the number of systems using ontologies is expected to increase, and given the open nature of the semantic Web, introduction of new ontologies and modifications to existing ones are to be expected. Dynamically handling such changes, without requiring human intervention, becomes crucial. This paper presents a framework that isolates groups of related axioms in an OWL ontology, so that a change in one or more axioms can be automatically localised to a part of the ontology.
---
paper_title: Changing Ontology Breaks Queries

paper_content:

Updating an ontology that is in use may result in inconsistencies between the ontology and the knowledge base, dependent ontologies and applications/services. Current research concentrates on the creation of ontologies and how to manage ontology changes in terms of mapping ontology versions and keeping consistent with the instances. Very little work investigated controlling the impact on dependent applications/services; which is the aim of the system presented in this paper. The approach we propose is to make use of ontology change logs to analyse incoming RDQL queries and amend them as necessary. Revised queries can then be used to query the ontology and knowledge base as requested by the applications and services. We describe our prototype system and discuss related problems and future directions.
---
paper_title: Enabling Active Ontology Change Management within Semantic Web-based Applications

paper_content:

Enabling traceable ontology changes is becoming a critical issue for ontology-based applications. Updating an ontology that is in use may result in inconsistencies between the ontology and the knowledge base, dependent ontologies and applications/services. Current research concentrates on the creation of ontologies and how to manage ontology changes in terms of mapping ontology versions and keeping consistent with the instances. Very little work investigated on-the-fly keeping track of ontology changes while update (active ontology versioning) and using these information to control the impact on dependent applications/services, which is the aim of our research presented in this thesis. The approach we propose is to make use of ontology change logs as a check-point to analyse changed entities related to the requested services via end-user’s incoming queries (RDQL/SPARQL) and amend them as necessary to maintain the validation and continuousness of the dependent application. Firstly, We build up Log Ontology I as the concept structure to organize and construct the change information, develop our prototype system to demonstrate how the change information retrieved from Log Ontology I could be used to control the impacts brought by the ontology changes on the dependent applications and services. And then, by analysing the limitations and difficulties of our prototype system in maintaining the services related to the more complex ontology changes, we identify that the problem which fails the system facing the more complex ontology changes is the inabilities of Log Ontology I to represent complex change information in a semantic fashion. Therefore, we retract to put more focuses on Log Ontology I to enable the implementation of the mechanism to on-the-fly keep track of ontology change information, forming Log Ontology II, in order to reserve the semantics of ontology change from the beginning of ontology update process. Finally we discuss the future direction in terms of how the improved Log Ontology II enables the better service validation and continuousness maintenance of changing-ontology-based applications.
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paper_title: Evolution Management for Interconnected Ontologies

paper_content:

Mappings between ontologies are easily harmed by changes in the ontologies. In this paper we explain a mechanism to define modular ontologies and mappings in a way that allows for local containment of terminological reasoning. We have also developed a change detection and analysis method that predicts the effect of changes on the concept hierarchy. This method determines whether the changes in one ontology affect the reasoning inside other ontologies or not. Together, these mechanisms allow ontologies to evolve without unpredictable effects on other ontologies. In this paper, we also apply these methods in a case study that is undertaken in a EU IST project.
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paper_title: Analyzing the evolution of life science ontologies and mappings

paper_content:

Ontologies are heavily developed and used in life sciences and undergo continuous changes. However, the evolution of life science ontologies and references to them (e.g., annotations) is not well understood and has received little attention so far. We therefore propose a generic framework for analyzing both the evolution of ontologies and the evolution of ontology-related mappings, in particular annotations referring to ontologies and similarity (match) mappings between ontologies. We use our framework for an extensive comparative evaluation of evolution measures for 16 life science ontologies. Moreover, we analyze the evolution of annotation mappings and ontology mappings for the Gene Ontology.
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paper_title: Ontology Evolution Issues in Adaptable Information Management Systems

paper_content:

Currently, ontology based information management systems have drawn great attentions. However, one of the challenges is how to manage the evolution of the ontology. If ontology evolution was not considered beforehand in the modeling phase of the system, then it may cause potential inconsistencies among the components of the ontology and the dependent applications. Besides the evolution of an ontology may interfere with the running of its dependent applications. Hence, in this paper the approaches of maintaining the consistency and keeping the continuousness of the dependent applications during the evolution are analyzed. Firstly, a virtual space based framework is put forward and most of the changes are to be made in the virtual space. Then two types of property changes are analyzed and solutions for processing them are given in detail. Besides, a register record approach is addressed for checking the dependency between the applications and the ontology schema.
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paper_title: Exelixis: evolving ontology-based data integration system

paper_content:

The evolution of ontologies is an undisputed necessity in ontology-based data integration. Yet, few research efforts have focused on addressing the need to reflect ontology evolution onto the underlying data integration systems. We present Exelixis, a web platform that enables query answering over evolving ontologies without mapping redefinition. This is achieved by rewriting queries among ontology versions. First, changes between ontologies are automatically detected and described using a high level language of changes. Those changes are interpreted as sound global-as-view (GAV) mappings. Then query expansion is applied in order to consider constraints from the ontology and unfolding to apply the GAV mappings. Whenever equivalent rewritings cannot be produced we a) guide query redefinition and/or b) provide the best "over-approximations", i.e. the minimally-containing and minimally-generalized rewritings. For the demonstration we will use four versions of the CIDOC-CRM ontology and real user queries to show the functionality of the system. Then we will allow conference participants to directly interact with the system to test its capabilities.
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paper_title: High-level change detection in RDF(S) KBs

paper_content:

With the increasing use of Web 2.0 to create, disseminate, and consume large volumes of data, more and more information is published and becomes available for potential data consumers, that is, applications/services, individual users and communities, outside their production site. The most representative example of this trend is Linked Open Data (LOD), a set of interlinked data and knowledge bases. The main challenge in this context is data governance within loosely coordinated organizations that are publishing added-value interlinked data on the Web, bringing together issues related to data management and data quality, in order to support the full lifecycle of data production, consumption, and management. In this article, we are interested in curation issues for RDF(S) data, which is the default data model for LOD. In particular, we are addressing change management for RDF(S) data maintained by large communities (scientists, librarians, etc.) which act as curators to ensure high quality of data. Such curated Knowledge Bases (KBs) are constantly evolving for various reasons, such as the inclusion of new experimental evidence or observations, or the correction of erroneous conceptualizations. Managing such changes poses several research problems, including the problem of detecting the changes (delta) between versions of the same KB developed and maintained by different groups of curators, a crucial task for assisting them in understanding the involved changes. This becomes all the more important as curated KBs are interconnected (through copying or referencing) and thus changes need to be propagated from one KB to another either within or across communities. This article addresses this problem by proposing a change language which allows the formulation of concise and intuitive deltas. The language is expressive enough to describe unambiguously any possible change encountered in curated KBs expressed in RDF(S), and can be efficiently and deterministically detected in an automated way. Moreover, we devise a change detection algorithm which is sound and complete with respect to the aforementioned language, and study appropriate semantics for executing the deltas expressed in our language in order to move backwards and forwards in a multiversion repository, using only the corresponding deltas. Finally, we evaluate through experiments the effectiveness and efficiency of our algorithms using real ontologies from the cultural, bioinformatics, and entertainment domains.
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paper_title: PROMPTDIFF: A Fixed-Point Algorithm for Comparing Ontology Versions

paper_content:

As ontology development becomes a more ubiquitous and collaborative process, the developers face the problem of maintaining versions of ontologies akin to maintaining versions of software code in large software projects. Versioning systems for software code provide mechanisms for tracking versions, checking out versions for editing, comparing different versions, and so on. We can directly reuse many of these mechanisms for ontology versioning. However, version comparison for code is based on comparing text files--an approach that does not work for comparing ontologies. Two ontologies can be identical but have different text representation. We have developed the PROMPTDIFF algorithm, which integrates different heuristic matchers for comparing ontology versions. We combine these matchers in a fixed-point manner, using the results of one matcher as an input for others until the matchers produce no more changes. The current implementation includes ten matchers but the approach is easily extendable to an arbitrary number of matchers. Our evaluation showed that PROMPTDIFF correctly identified 96% of the matches in ontology versions from large projects.
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paper_title: On Detecting High-Level Changes in RDF/S KBs

paper_content:

An increasing number of scientific communities rely on Semantic Web ontologies to share and interpret data within and across research domains. These common knowledge representation resources are usually developed and maintained manually and essentially co-evolve along with experimental evidence produced by scientists worldwide. Detecting automatically the differences between (two) versions of the same ontology in order to store or visualize their deltas is a challenging task for e-science. In this paper, we focus on languages allowing the formulation of concise and intuitive deltas, which are expressive enough to describe unambiguously any possible change and that can be effectively and efficiently detected. We propose a specific language that provably exhibits those characteristics and provide a change detection algorithm which is sound and complete with respect to the proposed language. Finally, we provide a promising experimental evaluation of our framework using real ontologies from the cultural and bioinformatics domains.
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paper_title: Managing ontology changes on the semantic Web

paper_content:

Although the ontology evolution plays a key role in the semantic Web, methods and tools to support it are missing. Thus, this paper proposes a component-based framework for managing ontology changes. The main functionalities of the OntoAnalyzer framework are: (1) to track changes and to formalize them using a language that we propose for representing ontology changes and (2) to identify changes a posteriori to ontology evolution and to analyze their effect on the ontology-based annotation of resources.
---
paper_title: High-level change detection in RDF(S) KBs

paper_content:

With the increasing use of Web 2.0 to create, disseminate, and consume large volumes of data, more and more information is published and becomes available for potential data consumers, that is, applications/services, individual users and communities, outside their production site. The most representative example of this trend is Linked Open Data (LOD), a set of interlinked data and knowledge bases. The main challenge in this context is data governance within loosely coordinated organizations that are publishing added-value interlinked data on the Web, bringing together issues related to data management and data quality, in order to support the full lifecycle of data production, consumption, and management. In this article, we are interested in curation issues for RDF(S) data, which is the default data model for LOD. In particular, we are addressing change management for RDF(S) data maintained by large communities (scientists, librarians, etc.) which act as curators to ensure high quality of data. Such curated Knowledge Bases (KBs) are constantly evolving for various reasons, such as the inclusion of new experimental evidence or observations, or the correction of erroneous conceptualizations. Managing such changes poses several research problems, including the problem of detecting the changes (delta) between versions of the same KB developed and maintained by different groups of curators, a crucial task for assisting them in understanding the involved changes. This becomes all the more important as curated KBs are interconnected (through copying or referencing) and thus changes need to be propagated from one KB to another either within or across communities. This article addresses this problem by proposing a change language which allows the formulation of concise and intuitive deltas. The language is expressive enough to describe unambiguously any possible change encountered in curated KBs expressed in RDF(S), and can be efficiently and deterministically detected in an automated way. Moreover, we devise a change detection algorithm which is sound and complete with respect to the aforementioned language, and study appropriate semantics for executing the deltas expressed in our language in order to move backwards and forwards in a multiversion repository, using only the corresponding deltas. Finally, we evaluate through experiments the effectiveness and efficiency of our algorithms using real ontologies from the cultural, bioinformatics, and entertainment domains.
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paper_title: Representation of Change in Controlled Medical Terminologies

paper_content:

Computer-based systems that support health care require large controlled terminologies to manage names and meanings of data elements. These terminologies are not static, because change in health care is inevitable. To share data and applications in health care, we need standards not only for terminologies and concept representation, but also for representing change. To develop a principled approach to managing change, we analyze the requirements of controlled medical terminologies and consider features that frame knowledge-representation systems have to offer. Based on our analysis, we present a concept model, a set of change operations, and a change-documentation model that may be appropriate for controlled terminologies in health care. We are currently implementing our modeling approach within a computational architecture.
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paper_title: A Framework for Ontology Evolution in Collaborative Environments

paper_content:

With the wider use of ontologies in the Semantic Web and as part of production systems, multiple scenarios for ontology maintenance and evolution are emerging. For example, successive ontology versions can be posted on the (Semantic) Web, with users discovering the new versions serendipitously; ontology-development in a collaborative environment can be synchronous or asynchronous; managers of projects may exercise quality control, examining changes from previous baseline versions and accepting or rejecting them before a new baseline is published, and so on. In this paper, we present different scenarios for ontology maintenance and evolution that we have encountered in our own projects and in those of our collaborators. We define several features that categorize these scenarios. For each scenario, we discuss the high-level tasks that an editing environment must support. We then present a unified comprehensive set of tools to support different scenarios in a single framework, allowing users to switch between different modes easily.
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paper_title: A Versioning and Evolution Framework for RDF Knowledge Bases

paper_content:

We present an approach to support the evolution of online, distributed, reusable, and extendable ontologies based on the RDF data model. The approach works on the basis of atomic changes, basically additions or deletions of statements to or from an RDF graph. Such atomic changes are aggregated to compound changes, resulting in a hierarchy of changes, thus facilitating the human reviewing process on various levels of detail. These derived compound changes may be annotated with meta-information and classified as ontology evolution patterns. The introduced ontology evolution patterns in conjunction with appropriate data migration algorithms enable the automatic migration of instance data in distributed environments.
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paper_title: C.: A pattern-based framework of change operators for ontology evolution

paper_content:

Change operators are the building blocks of ontology evolution. Different layers of change operators have been suggested. In this paper, we present a novel approach to deal with ontology evolution, in particular, change representation as a pattern-based layered operator framework. As a result of an empirical study, we identify four different levels of change operators based on the granularity, domain-specificity and abstraction of changes. The first two layers are based on generic structural change operators, whereas the next two layers are domain-specific change patterns. These layers of change patterns capture the real changes in the selected domains. We discuss identification and integration of the different layers.
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paper_title: A Component-Based Framework For Ontology Evolution

paper_content:

Support for ontology evolution becomes extremely important in distributed development and use of ontologies. Information about change can be represented in many different ways. We describe these different representations and propose a framework that integrates them. We show how different representations in the framework are related by describing some techniques and heuristics that supplement information in one representation with information from other representations. We present an ontology of change operations, which is the kernel of our framework. 1 Support for Ontology Evolution Ontologies are increasing in popularity, and researchers and developers use them in more and more application areas. Ontologies are used as shared vocabularies, to improve information retrieval, or to help data integration. Neither the ontology development itself nor its product—the ontology— is a single-person enterprise. Large standardized ontologies are often developed by several researchers in parallel (e.g. SUO1 [9]); a number of ontologies grow in the context of peer-to-peer applications (e.g. Edutella [5]); other ontologies are constructed dynamically [2]. Successful applications of ontologies in such uncontrolled, de-centralized and distributed environments require substantial support for change management in ontologies and ontology evolution [7]. Given an ontology O and its two versions, Vold and Vnew, a complete support for change management in an ontology environment includes support for the following tasks.2 Data Transformation: When an ontology version Vold is changed to Vnew, data described by Vold might need to translated to bring it in line with Vnew. For example, if we merge two concepts A and B from Vold into C in Vnew, we must combine instances of A and B as well. http://suo.ieee.org/ Note that Vnew is not necessarily a unique replacement for Vold. There might be several new versions based on the old version, and all of them could exist in parallel. The labels are just used to refer to two versions of an ontology where Vnew has evolved from Vold. Data Access: Even if data is not being transformed, if there exists data conforming to Vold, we often want to access this data and interpret it correctly via Vnew. That is, we should be able to retrieve all data that was accessible via queries in terms of Vold with queries in terms of Vnew. Furthermore, instances of concepts in Vold should be instances of equivalent concepts in Vnew. This task is a very common one in the context of the Semantic Web, where ontologies describe pieces of data on the web. Ontology Update: When we adapt a remote ontology to specific local needs, and the remote ontology changes, we must propagate the changes in the remote ontology to the adapted local ontology [8]. Consistent Reasoning: Ontologies, being formal descriptions, are often used as logical theories. When ontology changes occur, we must analyze the changes to determine whether specific axioms that were valid in Vold are still valid in Vnew. For example, it might be useful to know that a change does not affect the subsumption relationship between two concepts: if A v B is valid in Vold it is also valid in Vnew. While a change in the logical theory will always affects reasoning in general, answers to specific queries may remain unchanged. Verification and Approval: Sometimes developers need to verify and approve ontology changes. This situation often happens when several people are developing a centralized ontology, or when developers want to apply changes selectively. There must be a user interface that simplifies such verification and allows developers to accept or reject specific changes, enabling execution of some changes and rolling back of others. This list of tasks is not exhaustive. The tools that exist today support these tasks in isolation. For example, the KAON framework [10] supports evolution strategies, allowing developers to specify strategies for updating data when changes in an ontology occur. The SHOE versioning system specifies which versions of the ontology the current version is backward compatible with [3]. Many ontology-editing environments (e.g., Protege [1]) provide logs of changes between versions. While these tools support some of the ontologyevolution tasks, there is no interaction or sharing of information among the tools. However, many of these tasks require the same elements in the representation of change. Imple-
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paper_title: COnto-Diff: generation of complex evolution mappings for life science ontologies

paper_content:

Life science ontologies evolve frequently to meet new requirements or to better reflect the current domain knowledge. The development and adaptation of large and complex ontologies is typically performed collaboratively by several curators. To effectively manage the evolution of ontologies it is essential to identify the difference (Diff) between ontology versions. Such a Diff supports the synchronization of changes in collaborative curation, the adaptation of dependent data such as annotations, and ontology version management. We propose a novel approach COnto-Diff to determine an expressive and invertible diff evolution mapping between given versions of an ontology. Our approach first matches the ontology versions and determines an initial evolution mapping consisting of basic change operations (insert/update/delete). To semantically enrich the evolution mapping we adopt a rule-based approach to transform the basic change operations into a smaller set of more complex change operations, such as merge, split, or changes of entire subgraphs. The proposed algorithm is customizable in different ways to meet the requirements of diverse ontologies and application scenarios. We evaluate the proposed approach for large life science ontologies including the Gene Ontology and the NCI Thesaurus and compare it with PromptDiff. We further show how the Diff results can be used for version management and annotation migration in collaborative curation.
---
paper_title: Understanding ontology evolution: A change detection approach

paper_content:

In this article, we propose a change detection approach in the context of an ontology evolution framework for OWL DL ontologies. The framework allows ontology engineers to request and apply changes to the ontology they manage. Furthermore, the framework assures that the ontology and its depending artifacts remain consistent after changes have been applied. Innovative is that the framework includes a change detection mechanism that allows generating automatically a detailed overview of changes that have occurred based on a set of change definitions. In addition, different users (such as maintainers of depending artifacts) may have their own set of change definitions, which results into different overviews of the changes, each providing a different view on how the ontology has been changed. Using these change definitions, also different levels of abstraction are supported. Both features will enhance the understanding of the evolution of an ontology for different users.
---
paper_title: PROMPTDIFF: A Fixed-Point Algorithm for Comparing Ontology Versions

paper_content:

As ontology development becomes a more ubiquitous and collaborative process, the developers face the problem of maintaining versions of ontologies akin to maintaining versions of software code in large software projects. Versioning systems for software code provide mechanisms for tracking versions, checking out versions for editing, comparing different versions, and so on. We can directly reuse many of these mechanisms for ontology versioning. However, version comparison for code is based on comparing text files--an approach that does not work for comparing ontologies. Two ontologies can be identical but have different text representation. We have developed the PROMPTDIFF algorithm, which integrates different heuristic matchers for comparing ontology versions. We combine these matchers in a fixed-point manner, using the results of one matcher as an input for others until the matchers produce no more changes. The current implementation includes ten matchers but the approach is easily extendable to an arbitrary number of matchers. Our evaluation showed that PROMPTDIFF correctly identified 96% of the matches in ontology versions from large projects.
---
paper_title: Semantic Diff as the Basis for Knowledge Base Versioning

paper_content:

13th International Workshop on Non-Monotonic Reasoning (NMR). 14-16 May 2010, Toronto, Canada
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paper_title: On Detecting High-Level Changes in RDF/S KBs

paper_content:

An increasing number of scientific communities rely on Semantic Web ontologies to share and interpret data within and across research domains. These common knowledge representation resources are usually developed and maintained manually and essentially co-evolve along with experimental evidence produced by scientists worldwide. Detecting automatically the differences between (two) versions of the same ontology in order to store or visualize their deltas is a challenging task for e-science. In this paper, we focus on languages allowing the formulation of concise and intuitive deltas, which are expressive enough to describe unambiguously any possible change and that can be effectively and efficiently detected. We propose a specific language that provably exhibits those characteristics and provide a change detection algorithm which is sound and complete with respect to the proposed language. Finally, we provide a promising experimental evaluation of our framework using real ontologies from the cultural and bioinformatics domains.
---
paper_title: Managing ontology changes on the semantic Web

paper_content:

Although the ontology evolution plays a key role in the semantic Web, methods and tools to support it are missing. Thus, this paper proposes a component-based framework for managing ontology changes. The main functionalities of the OntoAnalyzer framework are: (1) to track changes and to formalize them using a language that we propose for representing ontology changes and (2) to identify changes a posteriori to ontology evolution and to analyze their effect on the ontology-based annotation of resources.
---
paper_title: High-level change detection in RDF(S) KBs

paper_content:

With the increasing use of Web 2.0 to create, disseminate, and consume large volumes of data, more and more information is published and becomes available for potential data consumers, that is, applications/services, individual users and communities, outside their production site. The most representative example of this trend is Linked Open Data (LOD), a set of interlinked data and knowledge bases. The main challenge in this context is data governance within loosely coordinated organizations that are publishing added-value interlinked data on the Web, bringing together issues related to data management and data quality, in order to support the full lifecycle of data production, consumption, and management. In this article, we are interested in curation issues for RDF(S) data, which is the default data model for LOD. In particular, we are addressing change management for RDF(S) data maintained by large communities (scientists, librarians, etc.) which act as curators to ensure high quality of data. Such curated Knowledge Bases (KBs) are constantly evolving for various reasons, such as the inclusion of new experimental evidence or observations, or the correction of erroneous conceptualizations. Managing such changes poses several research problems, including the problem of detecting the changes (delta) between versions of the same KB developed and maintained by different groups of curators, a crucial task for assisting them in understanding the involved changes. This becomes all the more important as curated KBs are interconnected (through copying or referencing) and thus changes need to be propagated from one KB to another either within or across communities. This article addresses this problem by proposing a change language which allows the formulation of concise and intuitive deltas. The language is expressive enough to describe unambiguously any possible change encountered in curated KBs expressed in RDF(S), and can be efficiently and deterministically detected in an automated way. Moreover, we devise a change detection algorithm which is sound and complete with respect to the aforementioned language, and study appropriate semantics for executing the deltas expressed in our language in order to move backwards and forwards in a multiversion repository, using only the corresponding deltas. Finally, we evaluate through experiments the effectiveness and efficiency of our algorithms using real ontologies from the cultural, bioinformatics, and entertainment domains.
---
paper_title: COnto-Diff: generation of complex evolution mappings for life science ontologies

paper_content:

Life science ontologies evolve frequently to meet new requirements or to better reflect the current domain knowledge. The development and adaptation of large and complex ontologies is typically performed collaboratively by several curators. To effectively manage the evolution of ontologies it is essential to identify the difference (Diff) between ontology versions. Such a Diff supports the synchronization of changes in collaborative curation, the adaptation of dependent data such as annotations, and ontology version management. We propose a novel approach COnto-Diff to determine an expressive and invertible diff evolution mapping between given versions of an ontology. Our approach first matches the ontology versions and determines an initial evolution mapping consisting of basic change operations (insert/update/delete). To semantically enrich the evolution mapping we adopt a rule-based approach to transform the basic change operations into a smaller set of more complex change operations, such as merge, split, or changes of entire subgraphs. The proposed algorithm is customizable in different ways to meet the requirements of diverse ontologies and application scenarios. We evaluate the proposed approach for large life science ontologies including the Gene Ontology and the NCI Thesaurus and compare it with PromptDiff. We further show how the Diff results can be used for version management and annotation migration in collaborative curation.
---
paper_title: Understanding ontology evolution: A change detection approach

paper_content:

In this article, we propose a change detection approach in the context of an ontology evolution framework for OWL DL ontologies. The framework allows ontology engineers to request and apply changes to the ontology they manage. Furthermore, the framework assures that the ontology and its depending artifacts remain consistent after changes have been applied. Innovative is that the framework includes a change detection mechanism that allows generating automatically a detailed overview of changes that have occurred based on a set of change definitions. In addition, different users (such as maintainers of depending artifacts) may have their own set of change definitions, which results into different overviews of the changes, each providing a different view on how the ontology has been changed. Using these change definitions, also different levels of abstraction are supported. Both features will enhance the understanding of the evolution of an ontology for different users.
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paper_title: Can you tell the difference between DL-Lite ontologies

paper_content:

We develop a formal framework for comparing different versions of DL-Lite ontologies. Four notions of difference and entailment between ontologies are introduced and their applications in ontology development and maintenance discussed. These notions are obtained by distinguishing between differences that can be observed among concept inclusions, answers to queries over ABoxes, and by taking into account additional context ontologies. We compare these notions, study their meta-properties, and determine the computational complexity of the corresponding reasoning tasks. Moreover, we show that checking difference and entailment can be automated by means of encoding into QBF satisfiability and using off-the-shelf QBF solvers. Finally, we explore the relationship between the notion of forgetting (or uniform interpolation) and our notions of difference between ontologies.
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paper_title: On the Foundations of Computing Deltas between RDF models

paper_content:

The ability to compute the differences that exist between two RDF models is an important step to cope with the evolving nature of the Semantic Web (SW). In particular, RDF Deltas can be employed to reduce the amount of data that need to be exchanged and managed over the network and hence build advanced SW synchronization and versioning services. By considering Deltas as sets of change operations, in this paper we study various RDF comparison functions in conjunction with the semantics of the underlying change operations and formally analyze their possible combinations in terms of correctness, minimality, semantic identity and redundancy properties.
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paper_title: SemVersion: A Versioning System for RDF and Ontologies

paper_content:

Knowledge domains and their semantic representations via ontologies are typically subject to change in practical applications. Additionally, engineering of ontologies often takes place in distributed settings where multiple independent users interact. Therefore, change management for ontologies becomes a crucial aspect for any kind of ontology management environment. This paper introduces a new RDF-centric versioning approach and an implementation called SemVersion. SemVersion provides structural and semantic versioning for RDF models and RDFbased ontology languages like RDFS. The requirements for our system are derived from a practical scenario in the librarian domain, i.e. the
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paper_title: Efficient Management of Biomedical Ontology Versions

paper_content:

Ontologies have become very popular in life sciences and other domains. They mostly undergo continuous changes and new ontology versions are frequently released. However, current analysis studies do not consider the ontology changes reflected in different versions but typically limit themselves to a specific ontology version which may quickly become obsolete. To allow applications easy access to different ontology versions we propose a central and uniform management of the versions of different biomedical ontologies. The proposed database approach takes concept and structural changes of succeeding ontology versions into account thereby supporting different kinds of change analysis. Furthermore, it is very space-efficient by avoiding redundant storage of ontology components which remain unchanged in different versions. We evaluate the storage requirements and query performance of the proposed approach for the Gene Ontology.
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paper_title: Coping with Changing Ontologies in a Distributed Environment

paper_content:

We discuss the problems associated with versioning ontologies in distributed environments. This is an important issue because ontologies can be of great use in structuring and querying intemet information, but many of the Intemet’s characteristics, such as distributed ownership, rapid evolution, and heterogeneity, make ontology management difficult. We present SHOE, a web-based knowledge representation language that supports multiple versions of ontologies. We then discuss the features of SHOE that address ontology versioning, the affects of ontology revision on SHOE web pages, and methods for implementing ontology integration using SHOE’s extension and version mechanisms.
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paper_title: Detecting Different Versions of Ontologies in Large Ontology Repositories

paper_content:

There exist a number of large repositories and search engines collecting ontologies from the web or directly from users. While mechanisms exist to help the authors of these ontologies manage their evolution locally, the links between different versions of the same ontology are often lost when the ontologies are collected by such systems. By inspecting a large collection of ontologies as part of the Watson search engine, we can see that this information is often encoded in the identifier of the ontologies, their URIs, using a variety of conventions and formats. We therefore devise an algorithm, the Ontology Version Detector, which implements a set of rules analyzing and comparing URIs of ontologies to discover versioning relations between ontologies. Through an experiment realized with 7000 ontologies, we show that such a simple and extensible approach actually provides large amounts of useful and relevant results. Indeed, the information derived from this algorithm helps us in understanding how version information is encoded in URIs and how ontologies evolve on the Web, ultimately supporting users in better exploiting the content of large ontology repositories.
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paper_title: A model theoretic semantics for ontology versioning

paper_content:

We show that the Semantic Web needs a formal semantics for the various kinds of links between ontologies and other documents. We provide a model theoretic semantics that takes into account ontology extension and ontology versioning. Since the Web is the product of a diverse community, as opposed to a single agent, this semantics accommodates different viewpoints by having different entailment relations for different ontology perspectives. We discuss how this theory can be practically applied to RDF and OWL and provide a theorem that shows how to compute perspective-based entailment using existing logical reasoners. We illustrate these concepts using examples and conclude with a discussion of future work.
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paper_title: Ontology versioning on the Semantic Web

paper_content:

Ontologies are often seen as basic building blocks for the Semantic Web, as they provide a reusable piece of knowledge about a specific domain. However, those pieces of knowledge are not static, but evolve over time. Domain changes, adaptations to different tasks, or changes in the conceptualization require modifications of the ontology. The evolution of ontologies causes operability problems, which will hamper their effective reuse. A versioning mechanism might help to reduce those problems, as it will make the relations between different revisions of an ontology explicit. This paper will discuss the problem of ontology versioning. Inspired by the work done in database schema versioning and program interface versioning, it will also propose building blocks for the most important aspects of a versioning mechanism, i.e., ontology identification and change specification.
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paper_title: Ontology versioning and change detection on the Web

paper_content:

To effectively use ontologies on the Web, it is essential that changes in ontologies are managed well. This paper analyzes the topic of ontology versioning in the context of the Web by looking at the characteristics of the version relation between ontologies and at the identification of online ontologies. Then, it describes the design of a web-based system that helps users to manage changes in ontologies. The system helps to keep different versions of web-based ontologies interoperable, by maintaining not only the transformations between ontologies, but also the conceptual relation between concepts in different versions. The system allows ontology engineers to compare versions of ontology and to specify these conceptual relations. For the visualization of differences, it uses an adaptable rule-based mechanism that finds and classifies changes in RDF-based ontologies.
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paper_title: Managing Change: An Ontology Version Control System

paper_content:

In this paper we present the basic requirements and initial design of a system which manages and facilitates changes to an OWL ontology in a multi-editor environment. This system uses a centralized client-server architecture in which the server maintains the current state and full history of all managed ontologies. Clients can access the current ontology version, all historical revisions, and differences between arbitrary revisions, as well as metadata associated with revisions. This system will be used by many other ontology based services, such as incremental reasoning, collaborative ontology development, advanced ontology search, and ontology module extraction. Taken holistically, this network of services will provide a rich environment for the development and management of ontology based information systems. 1 Motivation and Requirements We need for a system that manages access to a changing ontology. This requirement is experienced by a variety applications with different stakeholders. An illustrative use case is presented below. A large distributed organization requires integration and alignment of many heterogeneous data sources and information artifacts. They facilitate such integration by employing one or more expressive OWL ontologies that exist in defined relations to data sources, information artifacts, and an enterprise conceptual model. These ontologies, as a critical infrastructure components, have stakeholders throughout the organization and outside its boundaries. Further, they are developed and maintained concurrently by many parties. Individual stakeholders participate in the ontology engineering process in different ways. Some are primarily consumers, but may make detailed edits to areas of the ontologies critical to them. Others are charged with maintaining high-level ontology coherence and use an integrated ontology development environment, such as Protege-OWL, to collaborate with similar editors in realtime, leveraging tools to maintain a dynamic view of the ontology. All stakeholders rely on the ontologies being available and consistent across the organization. This use case illustrates a set of requirements: Client Performance The network is a potential bottleneck of any distributed or client-server system, but the critical work of ontology development is
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paper_title: Dynamic Ontologies on the Web

paper_content:

We discuss the problems associated with managing ontologies in distributed environments such as the Web. The Web poses unique problems for the use of ontologies because of the rapid evolution and autonomy of web sites. We present SHOE, a web-based knowledge representation language that supports multiple versions of ontologies. We describe SHOE in the terms of a logic that separates data from ontologies and allows ontologies to provide different perspectives on the data. We then discuss the features of SHOE that address ontology versioning, the effects of ontology revision on SHOE web pages, and methods for implementing ontology integration using SHOE’s extension and version mechanisms.
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paper_title: Ontology-based Web agents

paper_content:

This paper describes SHOE, a set of Simple HTML Ontology Extensions which allow World-Wide Web authors to annotate their pages with semantic knowledge such as “I am a graduate student” or “This person is my graduate advisor”. These annotations are expressed in terms of ontological knowledge which can be generated by using or extending standard ontologies available on the Web. This makes it possible to ask Web agent queries such as “Find me all graduate students in Maryland who are working on a project funded by DoD initiative 123-4567”, instead of simplistic keyword searches enabled by current search engines. We have also developed a web-crawling agent, Expos´ e, which interns SHOE knowledge from web documents, making these kinds queries a reality.
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paper_title: The Semantic Web Revisited

paper_content:

The article included many scenarios in which intelligent agents and bots undertook tasks on behalf of their human or corporate owners. Of course, shopbots and auction bots abound on the Web, but these are essentially handcrafted for particular tasks: they have little ability to interact with heterogeneous data and information types. Because we haven't yet delivered large-scale, agent-based mediation, some commentators argue that the semantic Web has failed to deliver. We argue that agents can only flourish when standards are well established and that the Web standards for expressing shared meaning have progressed steadily over the past five years
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Title: Ontology evolution: a process-centric survey

Section 1: Introduction
Description 1: Introduce the aim, motivation, and significance of ontology evolution, providing an overview of the paper's objectives and structure.

Section 2: Ontology evolution: definition and process model
Description 2: Define ontology evolution and discuss existing process models, deriving a unified ontology evolution cycle.

Section 3: Detecting the need for evolution
Description 3: Explain methods for detecting the need for ontology evolution by analyzing data and usage patterns.

Section 4: Suggesting ontology changes
Description 4: Detail approaches for suggesting changes to an ontology, focusing on unstructured knowledge from documents and structured knowledge from databases and online sources.

Section 5: Validating ontology changes
Description 5: Discuss methods to validate suggested changes, ensuring consistency and correctness through domain-based and formal properties-based validation.

Section 6: Assessing the impact of evolution
Description 6: Analyze the impact of ontology evolution on dependent applications, other ontologies, and formal criteria such as cost and benefits.

Section 7: Managing ontology changes
Description 7: Explore techniques for recording changes and managing different ontology versions, ensuring traceability and consistency across the ontology lifecycle.

Section 8: Conclusion
Description 8: Summarize the findings, discuss the contributions of the paper, and suggest directions for future research in ontology evolution.