A Survey of Volunteered Open Geo-Knowledge Bases in the Semantic Web
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paper_title: The computational geowiki: what, why, and how

paper_content:

Google Maps and its spin-offs are highly successful, but they have a major limitation: users see only pictures of geographic data. These data are inaccessible except by limited vendor-defined APIs, and associated user data are weakly linked to them. But some applications require access, specifically geowikis and computational geowikis. We present the design and implementation of a computational geowiki. We also show empirically that both geowiki and computational geowiki features are necessary for a representative domain, bicycling, because (a) cyclists have useful knowledge unavailable except from cyclists and (b) cyclist-oriented automatic route-finding is enhanced by user input. Finally, we derive design implications: for example, user contributions presented within a route description are useful, and wikis should support contribution of opinion as well as fact.
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paper_title: The wikification of GIS and its consequences: Or Angelina Jolie's new tattoo and the future of GIS

paper_content:

A method for encapsulating magnetic particles by enclosure within oil drops, mixing in an aqueous solution and dispersing the oil drops with the enclosed particles by application of an alternating magnetic field. The dispersed and oil covered particles are microencapsulated with at least one type of polymer.
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paper_title: Using Ontologies for Integrated Geographic Information Systems

paper_content:

Today, there is a huge amount of data gathered about the Earth, not only from new spatial information systems, but also from new and more sophisticated data collection technologies. This scenario leads to a number of interesting research challenges, such as how to integrate geographic information of different kinds. The basic motivation of this paper is to introduce a GIS architecture that can enable geographic information integration in a seamless and flexible way based on its semantic value and regardless of its representation. The proposed solution is an ontology-driven geographic information system that acts as a system integrator. In this system, an ontology is a component, such as the database, cooperating to fulfill the system’s objectives. By browsing through ontologies the users can be provided with information about the embedded knowledge of the system. Special emphasis is given to the case of remote sensing systems and geographic information systems. The levels of ontologies can be used to guide processes for the extraction of more general or more detailed information. The use of multiple ontologies allows the extraction of information in different stages of classification. The semantic integration of aerial images and GIS is a crucial step towards better geospatial modeling.
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paper_title: DBpedia: A Nucleus for a Web of Open Data

paper_content:

DBpedia is a community effort to extract structured information from Wikipedia and to make this information available on the Web. DBpedia allows you to ask sophisticated queries against datasets derived from Wikipedia and to link other datasets on the Web to Wikipedia data. We describe the extraction of the DBpedia datasets, and how the resulting information is published on the Web for human-andmachine-consumption. We describe some emerging applications from the DBpedia community and show how website authors can facilitate DBpedia content within their sites. Finally, we present the current status of interlinking DBpedia with other open datasets on the Web and outline how DBpedia could serve as a nucleus for an emerging Web of open data.
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paper_title: An intelligent bay geo-information retrieval approach based on Geo-ontology

paper_content:

In the era of information explosion, information retrieval has become a bottleneck in information sharing and integration. However currently, the existing information retrieval methods are mainly based on keyword matching, which can not fully take advantage of the information context and potential knowledge. All of these methods are particularly inefficient as to geospatial information which is more complex and unstructured. Nevertheless, geospatial ontology (Geo-ontology) has been used to enrich geospatial objects with semantic information which could be very helpful in the geospatial information retrieval and integration. And there is a wealth of relations between objects (such as the relation between bay and the inter-tidal zone) in bay field. Thus in this paper, an intelligent bay geo-information retrieval approach based on bay geo-information ontology has been proposed. Firstly, the procedure of establishing the bay geo-information ontology database is introduced. Secondly, both the intelligent retrieval mechanism and approach in bay geo-information are expatiated, which are used to convert the user retrievals request to semantic request and map the semantic request to concrete query of actual data source by adopting the knowledge that's explicitly expressed in formal ontology modeling language (OWL). Finally, the method was applied in the bay information management system, and the feasibility and efficacy of the geo-information retrieval approach is well verified.
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paper_title: Toward the semantic geospatial web

paper_content:

With the growth of the World Wide Web has come the insight that currently available methods for finding and using information on the web are often insufficient. In order to move the Web from a data repository to an information resource, a totally new way of organizing information is needed. The advent of the Semantic Web promises better retrieval methods by incorporating the data's semantics and exploiting the semantics during the search process. Such a development needs special attention from the geospatial perspective so that the particularities of geospatial meaning are captured appropriately. The creation the Semantic Geospatial Web needs the development multiple spatial and terminological ontologies, each with a formal semantics; the representation of those semantics such that they are available both to machines for processing and to people for understanding; and the processing of geospatial queries against these ontologies and the evaluation of the retrieval results based on the match between the semantics of the expressed information need and the available semantics of the information resources and search systems. This will lead to a new framework for geospatial information retrieval based on the semantics of spatial and terminological ontologies. By explicitly representing the role of semantics in different components of the information retrieval process (people, interfaces, search systems, and information resources), the Semantic Geospatial Web will enable users to retrieve more precisely the data they need, based on the semantics associated with these data.
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paper_title: LinkedGeoData -- Adding a Spatial Dimension to the Web of Data

paper_content:

In order to employ the Web as a medium for data and information integration, comprehensive datasets and vocabularies are required as they enable the disambiguation and alignment of other data and information. Many real-life information integration and aggregation tasks are impossible without comprehensive background knowledge related to spatial features of the ways, structures and landscapes surrounding us. In this paper we contribute to the generation of a spatial dimension for the Data Web by elaborating on how the collaboratively collected OpenStreetMap data can be transformed and represented adhering to the RDF data model. We describe how this data can be interlinked with other spatial data sets, how it can be made accessible for machines according to the linked data paradigm and for humans by means of a faceted geo-data browser.
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paper_title: GeoWordNet: a resource for geo-spatial applications

paper_content:

Geo-spatial ontologies provide knowledge about places in the world and spatial relations between them. They are fundamental in order to build semantic information retrieval systems and to achieve semantic interoperability in geo-spatial applications. In this paper we present GeoWordNet, a semantic resource we created from the full integration of GeoNames, other high quality resources and WordNet. The methodology we followed was largely automatic, with manual checks when needed. This allowed us accomplishing at the same time a never reached before accuracy level and a very satisfactory quantitative result, both in terms of concepts and geographical entities.
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paper_title: Geographical classification of documents using evidence from Wikipedia

paper_content:

Obtaining or approximating a geographic location for search results often motivates users to include place names and other geography-related terms in their queries. Previous work shows that queries that include geography-related terms correspond to a significant share of the users' demand. Therefore, it is important to recognize the association of documents to places in order to adequately respond to such queries. This paper describes strategies for text classification into geography-related categories, using evidence extracted from Wikipedia. We use terms that correspond to entry titles and the connections between entries in Wikipedia's graph to establish a semantic network from which classification features are generated. Results of experiments using a news data-set, classified over Brazilian states, show that such terms constitute valid evidence for the geographical classification of documents, and demonstrate the potential of this technique for text classification.
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paper_title: Geographical Information Retrieval with Ontologies of Place

paper_content:

Geographical context is required of many information retrieval tasks in which the target of the search may be documents, images or records which are referenced to geographical space only by means of place names. Often there may be an imprecise match between the query name and the names associated with candidate sources of information. There is a need therefore for geographical information retrieval facilities that can rank the relevance of candidate information with respect to geographical closeness as well as semantic closeness with respect to the topic of interest. Here we present an ontology of place that combines limited coordinate data with qualitative spatial relationships between places. This parsimonious model of place is intended to suppon information retrieval tasks that may be global in scope. The ontology has been implemented with a semantic modelling system linking non-spatial conceptual hierarchies with the place ontology. An hierarchical distance measure is combined with Euclidean distance between place centroids to create a hybrid spatial distance measure. This can be combined with thematic distance, based on classification semantics, to create an integrated semantic closeness measure that can be used for a relevance ranking of retrieved objects.
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paper_title: OpenStreetMap: User-Generated Street Maps

paper_content:

The OpenStreetMap project is a knowledge collective that provides user-generated street maps. OSM follows the peer production model that created Wikipedia; its aim is to create a set of map data that's free to use, editable, and licensed under new copyright schemes. A considerable number of contributors edit the world map collaboratively using the OSM technical infrastructure, and a core group, estimated at approximately 40 volunteers, dedicate their time to creating and improving OSM's infrastructure, including maintaining the server, writing the core software that handles the transactions with the server, and creating cartographical outputs. There's also a growing community of software developers who develop software tools to make OSM data available for further use across different application domains, software platforms, and hardware devices. The OSM project's hub is the main OSM Web site.
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paper_title: Semantically enriching VGI in support of implicit feedback analysis

paper_content:

In recent years, the proliferation of Volunteered Geographic Information (VGI) has enabled many Internet users to contribute to the construction of rich and increasingly complex spatial datasets. This growth of geo-referenced information and the often loose semantic structure of such data have resulted in spatial information overload. For this reason, a semantic gap has emerged between unstructured geo-spatial datasets and high-level ontological concepts. Filling this semantic gap can help reduce spatial information overload, therefore facilitating both user interactions and the analysis of such interaction. Implicit Feedback analysis is the focus of our work. In this paper we address this problem by proposing a system that executes spatial discovery queries. Our system combines a semantically-rich and spatially-poor ontology (DBpedia) with a spatially-rich and semantically-poor VGI dataset (OpenStreetMap). This technique differs from existing ones, such as the aggregated dataset LinkedGeoData, as it is focused on user interest analysis and takes map scale into account. System architecture, functionality and preliminary results gathered about the system performance are discussed.
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paper_title: Core Elements of Digital Gazetteers: Placenames, Categories, and Footprints

paper_content:

The core elements of a digital gazetteer are the placename itself, the type of place it labels, and a geographic footprint representing its location and possibly its extent. Such gazetteer data is an important component of indirect geographic referencing through placenames. Based on the gazetteer development work of the Alexandria Digital Library, this paper presents the nature of placenames, and the process of assigning categories to places based on the words in the placenames and other information, and discusses the nature of georeferencing places with geographic footprints.
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paper_title: Development and application of a metric on semantic nets

paper_content:

Motivated by the properties of spreading activation and conceptual distance, the authors propose a metric, called distance, on the power set of nodes in a semantic net. Distance is the average minimum path length over all pairwise combinations of nodes between two subsets of nodes. Distance can be successfully used to assess the conceptual distance between sets of concepts when used on a semantic net of hierarchical relations. When other kinds of relationships, like 'cause', are used, distance must be amended but then can again be effective. The judgements of distance significantly correlate with the distance judgements that people make and help to determine whether one semantic net is better or worse than another. The authors focus on the mathematical characteristics of distance that presents novel cases and interpretations. Experiments in which distance is applied to pairs of concepts and to sets of concepts in a hierarchical knowledge base show the power of hierarchical relations in representing information about the conceptual distance between concepts. >
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paper_title: DBpedia: A Nucleus for a Web of Open Data

paper_content:

DBpedia is a community effort to extract structured information from Wikipedia and to make this information available on the Web. DBpedia allows you to ask sophisticated queries against datasets derived from Wikipedia and to link other datasets on the Web to Wikipedia data. We describe the extraction of the DBpedia datasets, and how the resulting information is published on the Web for human-andmachine-consumption. We describe some emerging applications from the DBpedia community and show how website authors can facilitate DBpedia content within their sites. Finally, we present the current status of interlinking DBpedia with other open datasets on the Web and outline how DBpedia could serve as a nucleus for an emerging Web of open data.
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paper_title: Open Mind Common Sense: Knowledge Acquisition from the General Public

paper_content:

Open Mind Common Sense is a knowledge acquisition system designed to acquire commonsense knowledge from the general public over the web. We describe and evaluate our first fielded system, which enabled the construction of a 450,000 assertion commonsense knowledge base. We then discuss how our second-generation system addresses weaknesses discovered in the first. The new system acquires facts, descriptions, and stories by allowing participants to construct and fill in natural language templates. It employs word-sense disambiguation and methods of clarifying entered knowledge, analogical inference to provide feedback, and allows participants to validate knowledge and in turn each other.
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paper_title: Linked Data -- The story so far

paper_content:

The term “Linked Data” refers to a set of best practices for publishing and connecting structured data on the Web. These best practices have been adopted by an increasing number of data providers over the last three years, leading to the creation of a global data space containing billions of assertions— the Web of Data. In this article, the authors present the concept and technical principles of Linked Data, and situate these within the broader context of related technological developments. They describe progress to date in publishing Linked Data on the Web, review applications that have been developed to exploit the Web of Data, and map out a research agenda for the Linked Data community as it moves forward.
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paper_title: Freebase: a collaboratively created graph database for structuring human knowledge

paper_content:

Freebase is a practical, scalable tuple database used to structure general human knowledge. The data in Freebase is collaboratively created, structured, and maintained. Freebase currently contains more than 125,000,000 tuples, more than 4000 types, and more than 7000 properties. Public read/write access to Freebase is allowed through an HTTP-based graph-query API using the Metaweb Query Language (MQL) as a data query and manipulation language. MQL provides an easy-to-use object-oriented interface to the tuple data in Freebase and is designed to facilitate the creation of collaborative, Web-based data-oriented applications.
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paper_title: DBpedia Mobile: A Location-Enabled Linked Data Browser

paper_content:

In this demonstration, we present DBpedia Mobile, a location-centric DBpedia client application for mobile devices consisting of a map view and a Fresnel-based Linked Data browser. The DBpedia project extracts structured information from Wikipedia and publishes this information as Linked Data on the Web. The DBpedia dataset contains information about 2.18 million things, including almost 300,000 geographic locations. DBpedia is interlinked with various other location-related datasets. Based on the current GPS position of a mobile device, DBpedia Mobile renders a map indicating nearby locations from the DBpedia dataset. Starting from this map, users can explore background information about locations and can navigate into interlinked datasets. DBpedia Mobile demonstrates that the DBpedia dataset can serve as a useful starting point to explore the Geospatial Semantic Web using a mobile device.
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paper_title: YAGO : A Core of Semantic Knowledge Unifying WordNet and Wikipedia

paper_content:

We present YAGO, a light-weight and extensible ontology with high coverage and quality. YAGO builds on entities and relations and currently contains more than 1 million entities and 5 million facts. This includes the Is-A hierarchy as well as non-taxonomic relations between entities (such as HASONEPRIZE). The facts have been automatically extracted from Wikipedia and unified with WordNet, using a carefully designed combination of rule-based and heuristic methods described in this paper. The resulting knowledge base is a major step beyond WordNet: in quality by adding knowledge about individuals like persons, organizations, products, etc. with their semantic relationships - and in quantity by increasing the number of facts by more than an order of magnitude. Our empirical evaluation of fact correctness shows an accuracy of about 95%. YAGO is based on a logically clean model, which is decidable, extensible, and compatible with RDFS. Finally, we show how YAGO can be further extended by state-of-the-art information extraction techniques.
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paper_title: Geographical Linked Data: The Administrative Geography of Great Britain on the Semantic Web

paper_content:

Ordnance Survey, the national mapping agency of Great Britain, is investigating how semantic web technologies assist its role as a geographical information provider. A major part of this work involves the development of prototype products and datasets in RDF. This article discusses the production of an example dataset for the administrative geography of Great Britain, demonstrating the advantages of explicitly encoding topological relations between geographic entities over traditional spatial queries. We also outline how these data can be linked to other datasets on the web of linked data and some of the challenges that this raises.
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paper_title: Ontologies and knowledge bases: Towards a terminological clarification

paper_content:

The word \ontology" has recently gained a good popularity within the knowledge engineering community. However, its meaning tends to remain a bit vague, as the term is used in very difierent ways. Limiting our attention to the various proposals made in the current debate in AI, we isolate a number of interpretations, which in our opinion deserve a suitable clariflcation. We elucidate the implications of such various interpretations, arguing for the need of clear terminological choices regarding the technical use of terms like \ontology", \conceptualization" and \ontological commitment". After some comments on the use \Ontology" (with the capital \o") as a term which denotes a philosophical discipline, we analyse the possible confusion between an ontology intended as a particular conceptual framework at the knowledge level and an ontology intended as a concrete artifact at the symbol level, to be used for a given purpose. A crucial point in this clariflcation efiort is the careful analysis of Gruber’ s deflnition of an ontology as a speciflcation of a conceptualization.
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paper_title: LinkedGeoData -- Adding a Spatial Dimension to the Web of Data

paper_content:

In order to employ the Web as a medium for data and information integration, comprehensive datasets and vocabularies are required as they enable the disambiguation and alignment of other data and information. Many real-life information integration and aggregation tasks are impossible without comprehensive background knowledge related to spatial features of the ways, structures and landscapes surrounding us. In this paper we contribute to the generation of a spatial dimension for the Data Web by elaborating on how the collaboratively collected OpenStreetMap data can be transformed and represented adhering to the RDF data model. We describe how this data can be interlinked with other spatial data sets, how it can be made accessible for machines according to the linked data paradigm and for humans by means of a faceted geo-data browser.
---
paper_title: GeoWordNet: a resource for geo-spatial applications

paper_content:

Geo-spatial ontologies provide knowledge about places in the world and spatial relations between them. They are fundamental in order to build semantic information retrieval systems and to achieve semantic interoperability in geo-spatial applications. In this paper we present GeoWordNet, a semantic resource we created from the full integration of GeoNames, other high quality resources and WordNet. The methodology we followed was largely automatic, with manual checks when needed. This allowed us accomplishing at the same time a never reached before accuracy level and a very satisfactory quantitative result, both in terms of concepts and geographical entities.
---
paper_title: Geospatial Information Bottom-Up: A Matter of Trust and Semantics

paper_content:

Geographic Information Science and business are facing a new challenge: understanding and exploiting data and services emerging from online communities. In the emerging technologies of the social web, GI user roles switched from being data consumers to become data producers, the challenge we argue is in making this generated GI usable. As a use case we point to the increasing demands for up-to-date geographic information combined with the high cost of maintenance which present serious challenges to data providers. In this paper we argue that the social web combined with social network science present a unique opportunity to achieve the goal of reducing the cost of maintenance and update of geospatial data and providing a platform for bottom up approaches to GI. We propose to focus on web-based trust as a proxy measure for quality and to study its spatio-temporal dimensions. We also point to work on combining folksonomies with ontologies, allowing for alternative models of metadata and semantics as components of our proposed vision.
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paper_title: Geographical classification of documents using evidence from Wikipedia

paper_content:

Obtaining or approximating a geographic location for search results often motivates users to include place names and other geography-related terms in their queries. Previous work shows that queries that include geography-related terms correspond to a significant share of the users' demand. Therefore, it is important to recognize the association of documents to places in order to adequately respond to such queries. This paper describes strategies for text classification into geography-related categories, using evidence extracted from Wikipedia. We use terms that correspond to entry titles and the connections between entries in Wikipedia's graph to establish a semantic network from which classification features are generated. Results of experiments using a news data-set, classified over Brazilian states, show that such terms constitute valid evidence for the geographical classification of documents, and demonstrate the potential of this technique for text classification.
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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: OpenStreetMap: User-Generated Street Maps

paper_content:

The OpenStreetMap project is a knowledge collective that provides user-generated street maps. OSM follows the peer production model that created Wikipedia; its aim is to create a set of map data that's free to use, editable, and licensed under new copyright schemes. A considerable number of contributors edit the world map collaboratively using the OSM technical infrastructure, and a core group, estimated at approximately 40 volunteers, dedicate their time to creating and improving OSM's infrastructure, including maintaining the server, writing the core software that handles the transactions with the server, and creating cartographical outputs. There's also a growing community of software developers who develop software tools to make OSM data available for further use across different application domains, software platforms, and hardware devices. The OSM project's hub is the main OSM Web site.
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paper_title: WikiRelate! Computing Semantic Relatedness Using Wikipedia

paper_content:

Wikipedia provides a knowledge base for computing word relatedness in a more structured fashion than a search engine and with more coverage than WordNet. In this work we present experiments on using Wikipedia for computing semantic relatedness and compare it to WordNet on various benchmarking datasets. Existing relatedness measures perform better using Wikipedia than a baseline given by Google counts, and we show that Wikipedia outperforms WordNet when applied to the largest available dataset designed for that purpose. The best results on this dataset are obtained by integrating Google, WordNet and Wikipedia based measures. We also show that including Wikipedia improves the performance of an NLP application processing naturally occurring texts.
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paper_title: Towards an RDF encoding of ConceptNet

paper_content:

The possibility of relying on a rich background knowledge constitutes a key element for the development of more effective sentiment analysis and SW applications. In this paper, we propose to encode the wide knowledge base collected by Open Mind Common Sense initiative into ConceptNet, in a semantic aware format to make it directly available for Semantic Web applications. We also discuss how the encoding of ConceptNet into RDF can be beneficial to promote its connection with other resources such as WordNet and HEO ontology to further extend its knowledge base.
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paper_title: Semantic Wikipedia

paper_content:

Wikipedia is the world's largest collaboratively edited source of encyclopaedic knowledge. But in spite of its utility, its contents are barely machine-interpretable. Structural knowledge, e.,g. about how concepts are interrelated, can neither be formally stated nor automatically processed. Also the wealth of numerical data is only available as plain text and thus can not be processed by its actual meaning.We provide an extension to be integrated in Wikipedia, that allows the typing of links between articles and the specification of typed data inside the articles in an easy-to-use manner.Enabling even casual users to participate in the creation of an open semantic knowledge base, Wikipedia has the chance to become a resource of semantic statements, hitherto unknown regarding size, scope, openness, and internationalisation. These semantic enhancements bring to Wikipedia benefits of today's semantic technologies: more specific ways of searching and browsing. Also, the RDF export, that gives direct access to the formalised knowledge, opens Wikipedia up to a wide range of external applications, that will be able to use it as a background knowledge base.In this paper, we present the design, implementation, and possible uses of this extension.
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paper_title: Semantically enriching VGI in support of implicit feedback analysis

paper_content:

In recent years, the proliferation of Volunteered Geographic Information (VGI) has enabled many Internet users to contribute to the construction of rich and increasingly complex spatial datasets. This growth of geo-referenced information and the often loose semantic structure of such data have resulted in spatial information overload. For this reason, a semantic gap has emerged between unstructured geo-spatial datasets and high-level ontological concepts. Filling this semantic gap can help reduce spatial information overload, therefore facilitating both user interactions and the analysis of such interaction. Implicit Feedback analysis is the focus of our work. In this paper we address this problem by proposing a system that executes spatial discovery queries. Our system combines a semantically-rich and spatially-poor ontology (DBpedia) with a spatially-rich and semantically-poor VGI dataset (OpenStreetMap). This technique differs from existing ones, such as the aggregated dataset LinkedGeoData, as it is focused on user interest analysis and takes map scale into account. System architecture, functionality and preliminary results gathered about the system performance are discussed.
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paper_title: Volunteered Geographic Information: the nature and motivation of produsers

paper_content:

Advances in positioning, Web mapping, cellular communications and wiki technologies have surpassed the original visions of GSDI programs around the world. By tapping the distributed knowledge, personal time and energy of volunteer contributors, GI voluntarism is beginning to relocate and redistribute selected GI productive activities from mapping agencies to networks of non-state volunteer actors. Participants in the production process are both users and producers, or ‘produsers’ to use a recent neologism. Indeed, GI voluntarism ultimately has the potential to redistribute the rights to define and judge the value of the produced geographic information and of the new production system in general. The concept and its implementation present a rich collection of both opportunities and risks now being considered by leaders of public and private mapping organizations world-wide. In this paper, the authors describe and classify both the types of people who volunteer geospatial information and the nature of their contributions. Combining empirical research dealing with the Open Source software and Wikipedia communities with input from selected national mapping agencies and private companies, the authors offer different taxonomies that can help researchers clarify what is at stake with respect to geospatial information contributors. They identify early lessons which may be drawn from this research, and suggest questions which may be posed by large mapping organizations when considering the potential opportunities and risks associated with encouraging and employing Volunteered Geographic Information in their programs.
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paper_title: Description Logics as Ontology Languages for the Semantic Web

paper_content:

The vision of a Semantic Web has recently drawn considerable attention, both from academia and industry. Description logics are often named as one of the tools that can support the Semantic Web and thus help to make this vision reality.
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paper_title: Multi-source Toponym Data Integration and Mediation for a Meta-Gazetteer Service

paper_content:

A variety of gazetteers exist based on administrative or user contributed data. Each of these data sources has benefits for particular geographical analysis and information retrieval tasks but none is a one fit all solution. We present a mediation framework to access and integrate distributed gazetteer resources to build a meta-gazetteer that generates augmented versions of place name information. The approach combines different aspects of place name data from multiple gazetteer sources that refer to the same geographic place and employs several similarity metrics to identify equivalent toponyms.
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paper_title: A survey on ontology mapping

paper_content:

Ontology is increasingly seen as a key factor for enabling interoperability across heterogeneous systems and semantic web applications. Ontology mapping is required for combining distributed and heterogeneous ontologies. Developing such ontology mapping has been a core issue of recent ontology research. This paper presents ontology mapping categories, describes the characteristics of each category, compares these characteristics, and surveys tools, systems, and related work based on each category of ontology mapping. We believe this paper provides readers with a comprehensive understanding of ontology mapping and points to various research topics about the specific roles of ontology mapping.
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paper_title: A geo-service semantic integration in Spatial Data Infrastructures

paper_content:

In this paper we focus on the semantic heterogeneity problem as one of the main challenges in current Spatial Data Infrastructures (SDIs). We first report on the state of the art in reducing such a heterogeneity in SDIs. We then consider a particular geo-service integration scenario. We discuss an approach of how to semantically coordinate geographic services, which is based on a view of the semantics of web service coordination, implemented by using the Lightweight Coordination Calculus (LCC) language. In this approach, service providers share explicit knowledge of the interactions in which their services are engaged and these models of interaction are used operationally as the anchor for describing the semantics of the interaction. We achieve web service discovery and integration by using semantic matching between particular interactions and web service descriptions. For this purpose we introduce a specific solution, called structure preserving semantic matching. We present a real world application scenario to illustrate how semantic integration of geo web services can be performed by using this approach. Finally, we provide a preliminary evaluation of the solution discussed.
---
paper_title: Using Ontologies for Integrated Geographic Information Systems

paper_content:

Today, there is a huge amount of data gathered about the Earth, not only from new spatial information systems, but also from new and more sophisticated data collection technologies. This scenario leads to a number of interesting research challenges, such as how to integrate geographic information of different kinds. The basic motivation of this paper is to introduce a GIS architecture that can enable geographic information integration in a seamless and flexible way based on its semantic value and regardless of its representation. The proposed solution is an ontology-driven geographic information system that acts as a system integrator. In this system, an ontology is a component, such as the database, cooperating to fulfill the system’s objectives. By browsing through ontologies the users can be provided with information about the embedded knowledge of the system. Special emphasis is given to the case of remote sensing systems and geographic information systems. The levels of ontologies can be used to guide processes for the extraction of more general or more detailed information. The use of multiple ontologies allows the extraction of information in different stages of classification. The semantic integration of aerial images and GIS is a crucial step towards better geospatial modeling.
---
paper_title: YAGO : A Core of Semantic Knowledge Unifying WordNet and Wikipedia

paper_content:

We present YAGO, a light-weight and extensible ontology with high coverage and quality. YAGO builds on entities and relations and currently contains more than 1 million entities and 5 million facts. This includes the Is-A hierarchy as well as non-taxonomic relations between entities (such as HASONEPRIZE). The facts have been automatically extracted from Wikipedia and unified with WordNet, using a carefully designed combination of rule-based and heuristic methods described in this paper. The resulting knowledge base is a major step beyond WordNet: in quality by adding knowledge about individuals like persons, organizations, products, etc. with their semantic relationships - and in quantity by increasing the number of facts by more than an order of magnitude. Our empirical evaluation of fact correctness shows an accuracy of about 95%. YAGO is based on a logically clean model, which is decidable, extensible, and compatible with RDFS. Finally, we show how YAGO can be further extended by state-of-the-art information extraction techniques.
---
paper_title: The semantics of similarity in geographic information retrieval

paper_content:

Similarity measures have a long tradition in fields such as information retrieval, artificial intelligence, and cognitive science. Within the last years, these measures have been extended and reused to measure semantic similarity; i.e., for comparing meanings rather than syntactic differences. Various measures for spatial applications have been de- veloped, but a solid foundation for answering what they measure; how they are best ap- plied in information retrieval; which role contextual information plays; and how similarity values or rankings should be interpreted is still missing. It is therefore difficult to decide which measure should be used for a particular application or to compare results from dif- ferent similarity theories. Based on a review of existing similarity measures, we introduce a framework to specify the semantics of similarity. We discuss similarity-based information retrieval paradigms as well as their implementation in web-based user interfaces for geo- graphic information retrieval to demonstrate the applicability of the framework. Finally, we formulate open challenges for similarity research.
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paper_title: LinkedGeoData -- Adding a Spatial Dimension to the Web of Data

paper_content:

In order to employ the Web as a medium for data and information integration, comprehensive datasets and vocabularies are required as they enable the disambiguation and alignment of other data and information. Many real-life information integration and aggregation tasks are impossible without comprehensive background knowledge related to spatial features of the ways, structures and landscapes surrounding us. In this paper we contribute to the generation of a spatial dimension for the Data Web by elaborating on how the collaboratively collected OpenStreetMap data can be transformed and represented adhering to the RDF data model. We describe how this data can be interlinked with other spatial data sets, how it can be made accessible for machines according to the linked data paradigm and for humans by means of a faceted geo-data browser.
---
paper_title: GeoWordNet: a resource for geo-spatial applications

paper_content:

Geo-spatial ontologies provide knowledge about places in the world and spatial relations between them. They are fundamental in order to build semantic information retrieval systems and to achieve semantic interoperability in geo-spatial applications. In this paper we present GeoWordNet, a semantic resource we created from the full integration of GeoNames, other high quality resources and WordNet. The methodology we followed was largely automatic, with manual checks when needed. This allowed us accomplishing at the same time a never reached before accuracy level and a very satisfactory quantitative result, both in terms of concepts and geographical entities.
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paper_title: Inferring Geographical Ontologies from Multiple Resources for Geographical Information Retrieval

paper_content:

Most of the information available in electronic format, such as in the World Wide Web or in digital libraries, involves some kind of spatial awareness. For instance, news usually describe an event and the place where this event occurred: “Earthquake in Turkey”, “Visit of the Pope in Valencia”. Currently, the Information Retrieval (IR) research community is increasing its eorts dedicated to the retrieval of geographical information, as testified by the creation of the GeoCLEF 1 [5] evaluation exercise at the CLEF 2005, recently repeated in 2006, and the advances of the SPIRIT 2 project [6]. These eorts are aimed to the solution of typical issues of the geographical IR task. In many cases, explicit geographical information is missing from the documents, for instance the indication of a broader geographical entity is omitted when it is supposed to be well-known to the readers (e.g. usually France is not named in a news related to Paris). Another common problem is the synonymy, when there are many ways to indicate a geographical entity. This is particularly true for foreign names, where spelling variations are frequent. The solution to these problems has been generally individuated in the use of geographical-oriented ontologies [4, 6]. The manual construction of this kind of resources is usually a long, laborious process, and in many cases they are not freely available, such as the Getty Thesaurus of Geographical Names 3 (TGN). In order to overcome this issue, we made some attempts [2, 3] to use the geographical information included in WordNet, the wellknown general domain ontology developed at the University of Princeton [7]. Unfortunately, the quantity of geographical information included in WordNet is quite small. Although it is quite dicult to calculate the number of geographi
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paper_title: GeoMergeP: Geographic Information Integration through Enriched Ontology Matching

paper_content:

The combination of the use of advanced Information and Communication Technology, especially the Internet, to enable new ways of working, with the enhanced provision of information and interactive services accessible over different channels, is the foundation of a new family of information systems. Particularly, this information explosion on the Web, which threatens our ability to manage information, has affected the geographic information systems. Interoperability is a key word here, since it means, an increasing level of cooperation between information sources on national, regional and local levels; and requires new methods to develop interoperable geographic systems. In this paper, an ontology-driven system (GeoMergeP) is described for the semantic integration of geographic information sources. Particularly, we focus on how ontology matching can be enriched through the use of standards for implementing a semi-automatic matching approach. Then, the requirements and steps of the system are illustrated on the ISPRA (Italian Institute for Environmental Protection and Research) case study. Our preliminary results show that ontology matching can be improved; helping interoperating systems increase reliability of exchanged and shared information.
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paper_title: Geo linked data

paper_content:

Semantic Web applications that include map visualization clients are becoming common. When the description of an entity contains coordinate pairs, semantic applications often lay them as pins on maps provided by Web mapping service applications, such as Google Maps. Nowadays, semantic applications cannot guarantee that those maps provide spatial information related to the entities pinned to them. To address this issue, this paper proposes a refinement of Linked Data practices, named Geo Linked Data, which defines a lightweight semantic infrastructure to relate URIs that identify real world entities with geospatial Web resources, such as maps.
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paper_title: Approaches to Semantic Similarity Measurement for Geo‐Spatial Data: A Survey

paper_content:

Semantic similarity is central for the functioning of semantically enabled processing of geospatial data. It is used to measure the degree of potential semantic interoperability between data or different geographic information systems (GIS). Similarity is essential for dealing with vague data queries, vague concepts or natural language and is the basis for semantic information retrieval and integration. The choice of similarity measurement influences strongly the conceptual design and the functionality of a GIS. The goal of this article is to provide a survey presentation on theories of semantic similarity measurement and review how these approaches – originally developed as psychological models to explain human similarity judgment – can be used in geographic information science. According to their knowledge representation and notion of similarity we classify existing similarity measures in geometric, feature, network, alignment and transformational models. The article reviews each of these models and outlines its notion of similarity and metric properties. Afterwards, we evaluate the semantic similarity models with respect to the requirements for semantic similarity measurement between geospatial data. The article concludes by comparing the similarity measures and giving general advice how to choose an appropriate semantic similarity measure. Advantages and disadvantages point to their suitability for different tasks.
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paper_title: Multi-source Toponym Data Integration and Mediation for a Meta-Gazetteer Service

paper_content:

A variety of gazetteers exist based on administrative or user contributed data. Each of these data sources has benefits for particular geographical analysis and information retrieval tasks but none is a one fit all solution. We present a mediation framework to access and integrate distributed gazetteer resources to build a meta-gazetteer that generates augmented versions of place name information. The approach combines different aspects of place name data from multiple gazetteer sources that refer to the same geographic place and employs several similarity metrics to identify equivalent toponyms.
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paper_title: DBpedia Mobile: A Location-Enabled Linked Data Browser

paper_content:

In this demonstration, we present DBpedia Mobile, a location-centric DBpedia client application for mobile devices consisting of a map view and a Fresnel-based Linked Data browser. The DBpedia project extracts structured information from Wikipedia and publishes this information as Linked Data on the Web. The DBpedia dataset contains information about 2.18 million things, including almost 300,000 geographic locations. DBpedia is interlinked with various other location-related datasets. Based on the current GPS position of a mobile device, DBpedia Mobile renders a map indicating nearby locations from the DBpedia dataset. Starting from this map, users can explore background information about locations and can navigate into interlinked datasets. DBpedia Mobile demonstrates that the DBpedia dataset can serve as a useful starting point to explore the Geospatial Semantic Web using a mobile device.
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paper_title: Ontology‐based retrieval of geographic information

paper_content:

Discovering and accessing suitable geographic information (GI) in the open and distributed environments of current Spatial Data Infrastructures (SDIs) is a crucial task. Catalogues provide searchable repositories of information descriptions, but the mechanisms to support GI retrieval are still insufficient. Problems of semantic heterogeneity caused by the ambiguity of natural language can arise during keyword‐based search in catalogues and when formulating a query to access the discovered data. In this paper, we present an approach to ontology‐based GI retrieval that contributes to solving existing problems of semantic heterogeneity and hides most of the complexity of the required procedure from the requester. A query language and graphical user interface allow a requester to intuitively formulate a query using a well‐known domain vocabulary. From this query, an ontology concept is derived, which is then used to search a catalogue for a data source that provides all the information required to answer the ...
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paper_title: YAGO : A Core of Semantic Knowledge Unifying WordNet and Wikipedia

paper_content:

We present YAGO, a light-weight and extensible ontology with high coverage and quality. YAGO builds on entities and relations and currently contains more than 1 million entities and 5 million facts. This includes the Is-A hierarchy as well as non-taxonomic relations between entities (such as HASONEPRIZE). The facts have been automatically extracted from Wikipedia and unified with WordNet, using a carefully designed combination of rule-based and heuristic methods described in this paper. The resulting knowledge base is a major step beyond WordNet: in quality by adding knowledge about individuals like persons, organizations, products, etc. with their semantic relationships - and in quantity by increasing the number of facts by more than an order of magnitude. Our empirical evaluation of fact correctness shows an accuracy of about 95%. YAGO is based on a logically clean model, which is decidable, extensible, and compatible with RDFS. Finally, we show how YAGO can be further extended by state-of-the-art information extraction techniques.
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paper_title: A Survey of Named Entity Recognition and Classification

paper_content:

This survey covers fifteen years of research in the Named Entity Recognition and Classification (NERC) field, from 1991 to 2006. We report observations about languages, named entity types, domains and textual genres studied in the literature. From the start, NERC systems have been developed using hand-made rules, but now machine learning techniques are widely used. These techniques are surveyed along with other critical aspects of NERC such as features and evaluation methods. Features are word-level, dictionary-level and corpus-level representations of words in a document. Evaluation techniques, ranging from intuitive exact match to very complex matching techniques with adjustable cost of errors, are an indisputable key to progress.
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paper_title: Using co‐occurrence models for placename disambiguation

paper_content:

This paper describes the generation of a model capturing information on how placenames co-occur together. The advantages of the co-occurrence model over traditional gazetteers are discussed and the problem of placename disambiguation is presented as a case study. We begin by outlining the problem of ambiguous placenames. We demonstrate how analysis of Wikipedia can be used in the generation of a co-occurrence model. The accuracy of our model is compared to a handcrafted ground truth; then we evaluate alternative methods of applying this model to the disambiguation of placenames in free text (using the GeoCLEF evaluation forum). We conclude by showing how the inclusion of placenames in both the text and geographic parts of a query provides the maximum mean average precision and outline the benefits of a co-occurrence model as a data source for the wider field of geographic information retrieval (GIR).
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paper_title: Ontology-Based Spatial Query Expansion in Information Retrieval

paper_content:

Ontologies play a key role in Semantic Web research. A common use of ontologies in Semantic Web is to enrich the current Web resources with some well-defined meaning to enhance the search capabilities of existing web searching systems. This paper reports on how ontologies developed in the EU Semantic Web project SPIRIT are used to support retrieval of documents that are considered to be spatially relevant to users’ queries. The query expansion techniques presented in this paper are based on both a domain and a geographical ontology. The proposed techniques are distinguished from conventional ones in that a query is expanded by derivation of its geographical query footprint. The techniques are specially designed to resolve a query (such as castles near Edinburgh) that involves spatial terms (e.g. Edinburgh) and fuzzy spatial relationships (e.g. near) that qualify the spatial terms. Various factors are taken into account to support intelligent expansion of a spatial query, including, spatial terms as encoded in the geographical ontology, non-spatial terms as encoded in the domain ontology, as well as the semantics of the spatial relationships and their context of use. Some experiments have been carried out to evaluate the performance of the proposed techniques using sample realistic ontologies.
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paper_title: Approaches to disambiguating toponyms

paper_content:

Many approaches have been proposed in recent years in the context of Geographic Information Retrieval (GIR), mostly in order to deal with geographically constrained information in un-structured texts. Most of these approaches share a common scheme: in order to disambiguate a toponym t with n possible referents in a document d, they find a certain number of context toponyms c0,...,ck that are contained in d. A score for each referent is calculated according to the context toponyms, and the referent with the highest score is selected. According to the method used to calculate the score, Toponym Disambiguation (TD) methods may be grouped into three main categories, as proposed by [7]: • map-based: methods that use an explicit representation of toponyms on a map, for instance to calculate the average distance of unambiguous context toponyms from referents; • knowledge-based: methods that exploit external knowledge sources such as gazetteers, Wikipedia or ontologies to find disambiguation clues; • data-driven or supervised: methods based on machine learning techniques.
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paper_title: Geographical classification of documents using evidence from Wikipedia

paper_content:

Obtaining or approximating a geographic location for search results often motivates users to include place names and other geography-related terms in their queries. Previous work shows that queries that include geography-related terms correspond to a significant share of the users' demand. Therefore, it is important to recognize the association of documents to places in order to adequately respond to such queries. This paper describes strategies for text classification into geography-related categories, using evidence extracted from Wikipedia. We use terms that correspond to entry titles and the connections between entries in Wikipedia's graph to establish a semantic network from which classification features are generated. Results of experiments using a news data-set, classified over Brazilian states, show that such terms constitute valid evidence for the geographical classification of documents, and demonstrate the potential of this technique for text classification.
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paper_title: Geographical Information Retrieval with Ontologies of Place

paper_content:

Geographical context is required of many information retrieval tasks in which the target of the search may be documents, images or records which are referenced to geographical space only by means of place names. Often there may be an imprecise match between the query name and the names associated with candidate sources of information. There is a need therefore for geographical information retrieval facilities that can rank the relevance of candidate information with respect to geographical closeness as well as semantic closeness with respect to the topic of interest. Here we present an ontology of place that combines limited coordinate data with qualitative spatial relationships between places. This parsimonious model of place is intended to suppon information retrieval tasks that may be global in scope. The ontology has been implemented with a semantic modelling system linking non-spatial conceptual hierarchies with the place ontology. An hierarchical distance measure is combined with Euclidean distance between place centroids to create a hybrid spatial distance measure. This can be combined with thematic distance, based on classification semantics, to create an integrated semantic closeness measure that can be used for a relevance ranking of retrieved objects.
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paper_title: 2009. Semantic Rules for Context-Aware Geographical Information Retrieval

paper_content:

Geographical information retrieval (GIR) can benefit from context information to adapt the results to a user's current situation and personal preferences. In this respect, semantics-based GIR is especially challenging because context information - such as collected from sensors - is often provided through numeric values, which need to be mapped to ontological representations based on nominal symbols. The Web Ontology Language (OWL) lacks mathematical processing capabilities that require free variables, so that even basic comparisons and distance calculations are not possible. Therefore, the context information cannot be interpreted with respect to the task and the current user's preferences. In this paper, we introduce an approach based on semantic rules that adds these processing capabilities to OWL ontologies. The task of recommending personalized surf spots based on user location and preferences serves as a case study to evaluate the capabilities of semantic rules for context-aware geographical information retrieval. We demonstrate how the Semantic Web Rule Language (SWRL) can be utilized to model user preferences and how execution of the rules successfully retrieves surf spots that match these preferences. While SWRL itself enables free variables, mathematical functions are added via built-ins - external libraries that are dynamically loaded during rule execution. Utilizing the same mechanism, we demonstrate how SWRL built-ins can query the Semantic Sensor Web to enable the consideration of real-time measurements and thus make geographical information retrieval truly context-aware.
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paper_title: Description Logics as Ontology Languages for the Semantic Web

paper_content:

The vision of a Semantic Web has recently drawn considerable attention, both from academia and industry. Description logics are often named as one of the tools that can support the Semantic Web and thus help to make this vision reality.
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paper_title: Linked Data -- The story so far

paper_content:

The term “Linked Data” refers to a set of best practices for publishing and connecting structured data on the Web. These best practices have been adopted by an increasing number of data providers over the last three years, leading to the creation of a global data space containing billions of assertions— the Web of Data. In this article, the authors present the concept and technical principles of Linked Data, and situate these within the broader context of related technological developments. They describe progress to date in publishing Linked Data on the Web, review applications that have been developed to exploit the Web of Data, and map out a research agenda for the Linked Data community as it moves forward.
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paper_title: Freebase: a collaboratively created graph database for structuring human knowledge

paper_content:

Freebase is a practical, scalable tuple database used to structure general human knowledge. The data in Freebase is collaboratively created, structured, and maintained. Freebase currently contains more than 125,000,000 tuples, more than 4000 types, and more than 7000 properties. Public read/write access to Freebase is allowed through an HTTP-based graph-query API using the Metaweb Query Language (MQL) as a data query and manipulation language. MQL provides an easy-to-use object-oriented interface to the tuple data in Freebase and is designed to facilitate the creation of collaborative, Web-based data-oriented applications.
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paper_title: The semantics of similarity in geographic information retrieval

paper_content:

Similarity measures have a long tradition in fields such as information retrieval, artificial intelligence, and cognitive science. Within the last years, these measures have been extended and reused to measure semantic similarity; i.e., for comparing meanings rather than syntactic differences. Various measures for spatial applications have been de- veloped, but a solid foundation for answering what they measure; how they are best ap- plied in information retrieval; which role contextual information plays; and how similarity values or rankings should be interpreted is still missing. It is therefore difficult to decide which measure should be used for a particular application or to compare results from dif- ferent similarity theories. Based on a review of existing similarity measures, we introduce a framework to specify the semantics of similarity. We discuss similarity-based information retrieval paradigms as well as their implementation in web-based user interfaces for geo- graphic information retrieval to demonstrate the applicability of the framework. Finally, we formulate open challenges for similarity research.
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paper_title: LinkedGeoData -- Adding a Spatial Dimension to the Web of Data

paper_content:

In order to employ the Web as a medium for data and information integration, comprehensive datasets and vocabularies are required as they enable the disambiguation and alignment of other data and information. Many real-life information integration and aggregation tasks are impossible without comprehensive background knowledge related to spatial features of the ways, structures and landscapes surrounding us. In this paper we contribute to the generation of a spatial dimension for the Data Web by elaborating on how the collaboratively collected OpenStreetMap data can be transformed and represented adhering to the RDF data model. We describe how this data can be interlinked with other spatial data sets, how it can be made accessible for machines according to the linked data paradigm and for humans by means of a faceted geo-data browser.
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paper_title: GeoWordNet: a resource for geo-spatial applications

paper_content:

Geo-spatial ontologies provide knowledge about places in the world and spatial relations between them. They are fundamental in order to build semantic information retrieval systems and to achieve semantic interoperability in geo-spatial applications. In this paper we present GeoWordNet, a semantic resource we created from the full integration of GeoNames, other high quality resources and WordNet. The methodology we followed was largely automatic, with manual checks when needed. This allowed us accomplishing at the same time a never reached before accuracy level and a very satisfactory quantitative result, both in terms of concepts and geographical entities.
---
paper_title: OpenStreetMap: User-Generated Street Maps

paper_content:

The OpenStreetMap project is a knowledge collective that provides user-generated street maps. OSM follows the peer production model that created Wikipedia; its aim is to create a set of map data that's free to use, editable, and licensed under new copyright schemes. A considerable number of contributors edit the world map collaboratively using the OSM technical infrastructure, and a core group, estimated at approximately 40 volunteers, dedicate their time to creating and improving OSM's infrastructure, including maintaining the server, writing the core software that handles the transactions with the server, and creating cartographical outputs. There's also a growing community of software developers who develop software tools to make OSM data available for further use across different application domains, software platforms, and hardware devices. The OSM project's hub is the main OSM Web site.
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paper_title: Semantically enriching VGI in support of implicit feedback analysis

paper_content:

In recent years, the proliferation of Volunteered Geographic Information (VGI) has enabled many Internet users to contribute to the construction of rich and increasingly complex spatial datasets. This growth of geo-referenced information and the often loose semantic structure of such data have resulted in spatial information overload. For this reason, a semantic gap has emerged between unstructured geo-spatial datasets and high-level ontological concepts. Filling this semantic gap can help reduce spatial information overload, therefore facilitating both user interactions and the analysis of such interaction. Implicit Feedback analysis is the focus of our work. In this paper we address this problem by proposing a system that executes spatial discovery queries. Our system combines a semantically-rich and spatially-poor ontology (DBpedia) with a spatially-rich and semantically-poor VGI dataset (OpenStreetMap). This technique differs from existing ones, such as the aggregated dataset LinkedGeoData, as it is focused on user interest analysis and takes map scale into account. System architecture, functionality and preliminary results gathered about the system performance are discussed.
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paper_title: Ontology Quality by Detection of Conflicts in Metadata

paper_content:

ontologies continue to be an important component in techniques and applications in semantic technologies. Thus, it is necessary to evaluate their quality. Our focus is the detection of conflicting information (within an ontology) as a criterion to improve the quality of an ontology. We describe different types of conflicts and propose a rule-based approach by which human experts can define conditions that signal a conflict in data. These rules (represented using RuleML) are used to automatically detect conflicts in populated ontologies. We describe a prototype application and evaluate the applicability of this approach.
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paper_title: Modelling Ontology Evaluation and Validation

paper_content:

We present a comprehensive approach to ontology evaluation and validation, which have become a crucial problem for the development of semantic technologies. Existing evaluation methods are integrated into one sigle framework by means of a formal model. This model consists, firstly, of a meta-ontology called O 2 , that characterises ontologies as semiotic objects. Based on O 2 and an analysis of existing methodologies, we identify three main types of measures for evaluation: structural measures, that are typical of ontologies represented as graphs; functional measures, that are related to the intended use of an ontology and of its components; and usability-profiling measures, that depend on the level of annotation of the considered ontology. The meta-ontology is then complemented with an ontology of ontology validation called oQual, which provides the means to devise the best set of criteria for choosing an ontology over others in the context of a given project. Finally, we provide a small example of how to apply oQual-derived criteria to a validation case.
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paper_title: On Trusting Wikipedia

paper_content:

Given the fact that many people use Wikipedia , we should ask: Can we trust it? The empirical evidence suggests that Wikipedia articles are sometimes quite good but that they vary a great deal. As such, it is wrong to ask for a monolithic verdict on Wikipedia . Interacting with Wikipedia involves assessing where it is likely to be reliable and where not. I identify five strategies that we use to assess claims from other sources and argue that, to a greater of lesser degree, Wikipedia frustrates all of them. Interacting responsibly with something like Wikipedia requires new epistemic methods and strategies.
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paper_title: YAGO : A Core of Semantic Knowledge Unifying WordNet and Wikipedia

paper_content:

We present YAGO, a light-weight and extensible ontology with high coverage and quality. YAGO builds on entities and relations and currently contains more than 1 million entities and 5 million facts. This includes the Is-A hierarchy as well as non-taxonomic relations between entities (such as HASONEPRIZE). The facts have been automatically extracted from Wikipedia and unified with WordNet, using a carefully designed combination of rule-based and heuristic methods described in this paper. The resulting knowledge base is a major step beyond WordNet: in quality by adding knowledge about individuals like persons, organizations, products, etc. with their semantic relationships - and in quantity by increasing the number of facts by more than an order of magnitude. Our empirical evaluation of fact correctness shows an accuracy of about 95%. YAGO is based on a logically clean model, which is decidable, extensible, and compatible with RDFS. Finally, we show how YAGO can be further extended by state-of-the-art information extraction techniques.
---
paper_title: A semiotic metrics suite for assessing the quality of ontologies

paper_content:

A suite of metrics is proposed to assess the quality of an ontology. Drawing upon semiotic theory, the metrics assess the syntactic, semantic, pragmatic, and social aspects of ontology quality. We operationalize the metrics and implement them in a prototype tool called the Ontology Auditor. An initial validation of the Ontology Auditor on the DARPA Agent Markup Language (DAML) library of domain ontologies indicates that the metrics are feasible and highlights the wide variation in quality among ontologies in the library. The contribution of the research is to provide a theory-based framework that developers can use to develop high quality ontologies and that applications can use to choose appropriate ontologies for a given task.
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paper_title: Spatial Data Quality - Problems and Prospects

paper_content:

This paper reflects upon the topic of spatial data quality and the progress made in this field over the past 20-30 years. While international standards have been established, theoretical models of error developed, new visualization techniques introduced, and metadata now routinely documented for spatial datasets, difficulties nevertheless exist with the way data quality information is being described, communicated and applied in practice by users. These problems are identified and the paper suggests how the spatial information community might move forward to overcome these obstacles.
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paper_title: Geospatial Information Bottom-Up: A Matter of Trust and Semantics

paper_content:

Geographic Information Science and business are facing a new challenge: understanding and exploiting data and services emerging from online communities. In the emerging technologies of the social web, GI user roles switched from being data consumers to become data producers, the challenge we argue is in making this generated GI usable. As a use case we point to the increasing demands for up-to-date geographic information combined with the high cost of maintenance which present serious challenges to data providers. In this paper we argue that the social web combined with social network science present a unique opportunity to achieve the goal of reducing the cost of maintenance and update of geospatial data and providing a platform for bottom up approaches to GI. We propose to focus on web-based trust as a proxy measure for quality and to study its spatio-temporal dimensions. We also point to work on combining folksonomies with ontologies, allowing for alternative models of metadata and semantics as components of our proposed vision.
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paper_title: OntoQA: Metric-based ontology quality analysis

paper_content:

As the Semantic Web gains importance for sharing knowledge on the Internet this has lead to the development and publishing of many ontologies in different domains. When trying to reuse existing ontologies into their applications, users are faced with the problem of determining if an ontology is suitable for their needs. In this paper, we introduce OntoQA, an approach that analyzes ontology schemas and their populations (i.e. knowledgebases) and describes them through a well defined set of metrics. These metrics can highlight key characteristics of an ontology schema as well as its population and enable users to make an informed decision quickly. We present an evaluation of several ontologies using these metrics to demonstrate their applicability.
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paper_title: Spatial Data Quality and Error Analysis Issues: GIS Functions and Environmental Modeling

paper_content:

Organophilic clays and thixotropic cross-linkable polyester compositions containing the same are provided comprising an unsaturated polyester and an unsaturated aromatic monomer such as styrene having dispersed therein an organophilic clay gellant comprising the reaction product of a smectite-type clay having a cation exchange capacity of at least 75 milliequivalents per 100 grams of clay and a methyl benzyl dialkyl ammonium compound or a dibenzyl dialkyl ammonium compound, said alkyl groups comprising long chain alkyl radicals having from 8 to 20 carbon atoms, wherein at least 5% of said long chains contain 8 to 14 carbon atoms and preferably at least 20% have 12 carbon atoms, the amount of said ammonium compound reacted with said clay being from 100 to 130 milliequivalents per 100 grams of clay based on 100% active clay. The polyester commpositions are prepared by a pregel method in which the organophilic clay gellant is mixed with the unsaturated aromatic monomer under high shear to form a pregel and the pregel is then combined with an unsaturated polyester to form the thixotropic compositions.
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paper_title: Internet encyclopaedias go head to head

paper_content:

Jimmy Wales' Wikipedia comes close to Britannica in terms of the accuracy of its science entries, a Nature investigation finds. UPDATE: see details of how the data were collected for this article in the supplementary information. UPDATE 2 (28 March 2006). The results reported in this news story and their interpretation have been disputed by Encyclopaedia Britannica. Nature responded to these objections .
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paper_title: Towards quality metrics for OpenStreetMap

paper_content:

Volunteered Geographic Information (VGI) is currently a "hot topic" in the GIS community. The OpenStreetMap (OSM) project is one of the most popular and well supported examples of VGL Traditional measures of spatial data quality are often not applicable to OSM as in many cases it is not possible to access ground-truth spatial data for all regions mapped by OSM. We investigate to develop measures of quality for OSM which operate in an unsupervised manner without reference to a "trusted" source of ground-truth data. We provide results of analysis of OSM data from several European countries. The results highlight specific quality issues in OSM. Results of comparing OSM with ground-truth data for Ireland are also presented.
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paper_title: Empirical Insights on a Value of Ontology Quality in Ontology-Driven Web Search

paper_content:

Nowadays ontologies are often used to improve search applications. Quality of ontology plays an important role in these applications. An important body of work exists in both information retrieval evaluation and ontology quality assessment areas. However, there is a lack of task- and scenario-based quality assessment methods. In this paper we discuss a framework to assess fitness of ontology for use in ontology-driven Web search. We define metrics for ontology fitness to particular search tasks and metrics for ontology capability to enhance recall and precision. Further, we discuss results of a preliminary experiment showing applicability of the proposed framework and a value of ontology quality in ontology-driven Web search.
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paper_title: Toward a Formal Evaluation of Ontology Quality

paper_content:

The present invention relates to novel hydrodipyranophthalazine compounds of the formula: wherein R1 = hydrogen or lower alkyl, R2 = hydrogen, chlorine or bromine, R3 = hydrogen or aralkyl if R2 = hydrogen, R3 = bromine or alkoxy if R2 = bromine, R3 = chlorine or alkoxy if R2 = chlorine, or wherein R4 = hydrogen, halogen, trifluoromethyl, alkyl, alkoxyl, alkylenedioxy, a possibly substituted amino group, or a nitro group, THE 4,4'-BOND IS SATURATED OR UNSATURATED, AND ACID-ADDITION SALTS OF THESE COMPOUNDS.
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paper_title: Consuming Multiple Linked Data Sources: Challenges and Experiences

paper_content:

Linked Data has provided the means for a large number of considerable knowledge resources to be published and interlinked utilising Semantic Web technologies. However it remains difficult to make use of this 'Web of Data' fully, due to its inherently distributed and often inconsistent nature. In this paper we introduce core challenges faced when consuming multiple sources of Linked Data, focussing in particular on the problem of querying. We compare both URI resolution and federated query approaches, and outline the experiences gained in the development of an application which utilises a hybrid approach to consume Linked Data from the unbounded web.
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paper_title: Challenges and resources for evaluating geographical IR

paper_content:

This paper discusses evaluation of Geo-IR systems, arguing for a separate study of the different algorithmic components involved. It presents existing resources for evaluating the different components, together with a review on previous results in the area.
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paper_title: When owl: sameAs isn't the Same: An Analysis of Identity Links on the Semantic Web

paper_content:

In Linked Data, the use of owl:sameAs is ubiquitous in ‘inter-linking’ data-sets. However, there is a lurking suspicion within the Linked Data community that this use of owl:sameAs may be somehow incorrect, in particular with regards to its interactions with inference. In fact, owl:sameAs can be considered just one type of ‘identity link,’ a link that declares two items to be identical in some fashion. After reviewing the definitions and history of the problem of identity in philosophy and knowledge representation, we outline four alternative readings of owl:sameAs, showing with examples how it is being (ab)used on the Web of data. Then we present possible solutions to this problem by introducing alternative identity links that rely on named graphs.
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paper_title: What OWL Has Done for Geography and Why We Don't Need it to Map Read

paper_content:

This position paper describes our experiences of authoring a geospatial ontology in the domain of hydrology topography, giving examples of where we find the additional functionality of OWL 1.1 useful. We also comment on approaches to combining spatial and semantic reasoning. We contend that spatial reasoning can be best achieved through a combination of semantic and spatial database technologies working together and spatial relationships expressed in OWL need to represent more than just spatial logics.
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paper_title: Challenges for indexing in GIR

paper_content:

Geographic information retrieval (GIR) has been evaluated in campaigns such as GeoCLEF, GikiP, and GikiCLEF [8, 12, 11]. Surprisingly, most results from these evaluations showed that adding more geographic knowledge typically had little or no effect on performance of GIR systems or that it even decreases performance compared to traditional (textual) information retrieval baselines (see e.g. [4]). In this position paper, current challenges of how to further improve the creation, structure and access to geographic resources (for simplicity, called the geographic index in the rest of this note) are discussed. The major challenges for indexing in GIR discussed in this note are applying methods beyond named entity recognition to identify geographic references, integrating additional, proven methods from related research areas such as question answering for semantic indexing, and aiming for better index support to interpret geographic relations. After summarizing the state of the art in indexing for GIR as it has evolved from GIR evaluation campaigns, research challenges and directions for future research are presented.
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paper_title: Evaluating GIR: geography-oriented or user-oriented?

paper_content:

Geographic terms appear very often in user queries. Many geographic references are present in query log-files. Examples found in different log files [6] include question answering style queries such as "What time is it in West Samoa?", terms within book titles like "Death in Venice", detailed street addresses and single term city names.
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paper_title: Building place ontologies for the semantic web:: issues and approaches

paper_content:

Place geo-ontologies have a key role to play in the development of thegeospatial-semantic web, with regard to facilitating the search for geographical information and resources. They normally hold large amounts of geographicinformation and undergo a continuous process of revision and update. This papers reviews the limitations of the OWL ontology language for the representation of Place and proposes two novel approaches to frameworks that combine rules and OWL for building and managing Place ontologies.
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paper_title: Towards quality metrics for OpenStreetMap

paper_content:

Volunteered Geographic Information (VGI) is currently a "hot topic" in the GIS community. The OpenStreetMap (OSM) project is one of the most popular and well supported examples of VGL Traditional measures of spatial data quality are often not applicable to OSM as in many cases it is not possible to access ground-truth spatial data for all regions mapped by OSM. We investigate to develop measures of quality for OSM which operate in an unsupervised manner without reference to a "trusted" source of ground-truth data. We provide results of analysis of OSM data from several European countries. The results highlight specific quality issues in OSM. Results of comparing OSM with ground-truth data for Ireland are also presented.
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paper_title: The place of place in geographical IR

paper_content:

Let us deﬁne geographical IR (GIR) as the activity whosepurpose is to retrieve information in a geographically-awareway. In other words, considering the geographical dimensionas special. GIR presupposes two things:• the possibility to associate to (possibly retrieve from)the collection geographical information• the existence (or the possibility of creation) of semanticrepositories that allow geographical reasoning, hence-forth called geo-ontologies.The most common kind of collections for GIR so far arethe Web and other document collections, which are mainlytextual. This paper is concerned with the non-trivial rela-tionship between reference to place in natural language (NL)and common GIR assumptions. There are two main ways inwhich NL texts and GIR meet: in the attempt to derive orpopulate geo-ontologies from text itself, and in the attemptto label Web pages with what is called geo-scopes, derivingthese from clues in the pages themselves.We will survey brieﬂy the two, noting in passing that bothapproaches are bottom-up in the sense that they look atthe texts, but the second makes use of a prior informationsource, a geo-ontology, which is typically top-down (see Geo-Net-PT01 in Table 1).
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paper_title: Empirical Insights on a Value of Ontology Quality in Ontology-Driven Web Search

paper_content:

Nowadays ontologies are often used to improve search applications. Quality of ontology plays an important role in these applications. An important body of work exists in both information retrieval evaluation and ontology quality assessment areas. However, there is a lack of task- and scenario-based quality assessment methods. In this paper we discuss a framework to assess fitness of ontology for use in ontology-driven Web search. We define metrics for ontology fitness to particular search tasks and metrics for ontology capability to enhance recall and precision. Further, we discuss results of a preliminary experiment showing applicability of the proposed framework and a value of ontology quality in ontology-driven Web search.
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paper_title: The digital earth: Understanding our planet in the 21st century

paper_content:

The hard part of taking advantage of this flood of geospatial information will be making sense of it. turning raw data into understandable information. Today, we often find that we have more information than we know what to do with. The Landsat program, designed to help us understand the global environment, is a good example. The Landsat satellite is capable of taking a complete photograph of the entire planet every two weeks, and it's been collecting data for more than 20 years. In spite of the great need for that information, the vast majority of those images have never fired a single neuron in a single human brain. Instead, they are stored in electronic silos of data. We used to have an agricultural policy where we stored grain in Midwestern silos and let it rot while millions of people starved to death. Now we have an insatiable hunger for knowledge. Yet a great deal of data remains unused.
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paper_title: Citizens as Sensors: The World of Volunteered Geography

paper_content:

In recent months there has been an explosion of interest in using the Web to create, assemble, and disseminate geographic information provided voluntarily by individuals. Sites such as Wikimapia and OpenStreetMap are empowering citizens to create a global patchwork of geographic information, while Google Earth and other virtual globes are encouraging volunteers to develop interesting applications using their own data. I review this phenomenon, and examine associated issues: what drives people to do this, how accurate are the results, will they threaten individual privacy, and how can they augment more conventional sources? I compare this new phenomenon to more traditional citizen science and the role of the amateur in geographic observation.
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paper_title: Toward the semantic geospatial web

paper_content:

With the growth of the World Wide Web has come the insight that currently available methods for finding and using information on the web are often insufficient. In order to move the Web from a data repository to an information resource, a totally new way of organizing information is needed. The advent of the Semantic Web promises better retrieval methods by incorporating the data's semantics and exploiting the semantics during the search process. Such a development needs special attention from the geospatial perspective so that the particularities of geospatial meaning are captured appropriately. The creation the Semantic Geospatial Web needs the development multiple spatial and terminological ontologies, each with a formal semantics; the representation of those semantics such that they are available both to machines for processing and to people for understanding; and the processing of geospatial queries against these ontologies and the evaluation of the retrieval results based on the match between the semantics of the expressed information need and the available semantics of the information resources and search systems. This will lead to a new framework for geospatial information retrieval based on the semantics of spatial and terminological ontologies. By explicitly representing the role of semantics in different components of the information retrieval process (people, interfaces, search systems, and information resources), the Semantic Geospatial Web will enable users to retrieve more precisely the data they need, based on the semantics associated with these data.
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paper_title: Evaluating GIR: geography-oriented or user-oriented?

paper_content:

Geographic terms appear very often in user queries. Many geographic references are present in query log-files. Examples found in different log files [6] include question answering style queries such as "What time is it in West Samoa?", terms within book titles like "Death in Venice", detailed street addresses and single term city names.
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Title: A Survey of Volunteered Open Geo-Knowledge Bases in the Semantic Web

Section 1: Introduction
Description 1: Introduce the concept of geo-wikification, the impact of neogeography on various sectors, and the emergence of the Semantic Geospatial Web. Emphasize the synergy between crowdsourcing, VGI, and the Semantic Geospatial Web, and outline the contents of the survey.

Section 2: Survey of Open Linked Geo-Knowledge Bases
Description 2: Provide a comprehensive survey of open, collaborative geo-knowledge bases, including definitions of related terms and descriptions of prominent projects such as ConceptNet, DBpedia, Freebase, GeoNames, GeoWordNet, LinkedGeoData, OpenCyc, and others. Summarize the characteristics and contributions of each knowledge base.

Section 3: Mapping, Aligning, and Merging Geo-Knowledge Bases
Description 3: Discuss the challenges and methods for integrating heterogeneous geo-knowledge bases, including ontology alignment and merging techniques. Highlight specific integration projects and methodologies.

Section 4: Ontology-powered Geographic Information Retrieval (GIR)
Description 4: Survey recent work in the use of geo-knowledge bases to enhance Geographic Information Retrieval (GIR), covering key areas such as Named Entity Recognition and Classification, toponym disambiguation, and toponym resolution. Discuss the benefits and challenges of using ontologies in GIR.

Section 5: The OSM Semantic Network
Description 5: Describe the creation and application of the OSM Semantic Network, including the development of a web crawler to extract semantic data from OpenStreetMap (OSM) and linking it to DBpedia. Discuss the significance of this resource in the context of geo-knowledge bases.

Section 6: The Quality of Crowdsourced Geo-Knowledge Bases
Description 6: Examine the methods for assessing the quality of geo-knowledge bases, particularly those that are crowdsourced. Discuss the trade-offs between coverage and precision, and present approaches for evaluating the quality of both class-level schemas and instance-level data.

Section 7: Current Limitations of Geo-Knowledge Bases and GIR
Description 7: Identify and analyze the current limitations and challenges of geo-knowledge bases and GIR, including issues of ambiguity, coverage, quality, expressivity, and complexity. Discuss the implications of these challenges for the future of geo-information systems.

Section 8: Conclusions and Future Work
Description 8: Summarize the findings of the survey and discuss the future directions for research in open geo-knowledge bases and GIR. Emphasize the importance of developing usable applications and interfaces to leverage these knowledge bases effectively.