Modellare il mercato dell'arte nel Web semantico. Un'analisi preliminare
10.6092/issn.2532-8816/17208
Il seguente articolo presenta lo stadio attuale di un progetto in corso presso la Fondazione Federico Zeri volto alla modellizzazione del mercato dell'arte a partire dal riconoscimento delle specificità che caratterizzano questo settore e dai dati raccolti dall’istituto di ricerca bolognese nel corso del trattamento delle proprie collezioni documentarie. In particolare, il saggio fornisce un'analisi preliminare del dominio volta a guidare la definizione di un'ontologia che sia in grado di descrivere i principali agenti, eventi e fonti che lo definiscono e che ne permettono l’indagine. Dopo aver fornito i riferimenti ad altre ontologie e modelli presi in esame nel corso del progetto, l’articolo indaga in profondità il mondo del mercato utilizzando la metodologia SAMOD: per ognuno dei tre moduli in cui è stata suddivisa l’ontologia vengono quindi proposti scenari, esempi e domande di competenza, elencate le entità più rilevanti e proposti sia un allineamento con le ontologie esistenti, sia alcune necessarie integrazioni.
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Modelling The Art Market in The Semantic Web. A Preliminary Analysis
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Francesca Mambelli
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Modelling The Art Market in The Semantic Web. A Preliminary Analysis
https://umanisticadigitale.unibo.it/article/download/17208/17044
   Umanistica Digitale – ISSN: 2532-8816 – n. 16, 2023
F. Mambelli, M. Veggi – Modelling The Art Market in The Semantic Web. A Preliminary Analysis
DOI: http://doi.org/10.6092/issn.2532-8816/17208


       Modelling The Art Market in The Semantic Web. A
                    Preliminary Analysis

                                               Mambelli Francesca

                      Fondazione Federico Zeri - University of Bologna, Bologna, Italy
                                     francesca.mambelli6@unibo.it



                                                  Veggi Manuele

                                  “Sapienza” University of Rome, Rome, Italy
                                        manuele.veggi@uniroma1.it




         Abstract

The paper presents the current stage of an ongoing project at the Fondazione Federico Zeri,
aimed at the modelling of the art market starting from the recognition of the peculiarities of this
sector and relying on the data collected by this institute during its research activities on its
documentary collection. Specifically, this essay provides a preliminary analysis of the domain,
aimed at guiding in the development of an ontology able to describe agents, events and sources
which define the art market and enable its investigation. The recognition of existing conceptual
models is hence followed by a reconstruction of the studied domain thanks to motivating
scenario, examples and competency questions collected during the first iteration of the SAMOD
methodology. For each scenario, the paper will provide the most relevant entities and will draft
an alignment with existing ontologies, as well as propose necessary integrations.
Keywords: Ontology engineering, Digital Art History, Art Market, Knowledge Representation,
Semantic Web, Dossier Digital Art History
Il seguente articolo presenta lo stadio attuale di un progetto in corso presso la Fondazione Federico Zeri volto alla
modellizzazione del mercato dell'arte a partire dal riconoscimento delle specificità che caratterizzano questo settore
e dai dati raccolti dall’istituto di ricerca bolognese nel corso del trattamento delle proprie collezioni documentarie.
In particolare, il saggio fornisce un'analisi preliminare del dominio volta a guidare la definizione di un'ontologia
che sia in grado di descrivere i principali agenti, eventi e fonti che lo definiscono e che ne permettono l’indagine.
Dopo aver fornito i riferimenti ad altre ontologie e modelli presi in esame nel corso del progetto, l’articolo indaga
in profondità il mondo del mercato utilizzando la metodologia SAMOD: per ognuno dei tre moduli in cui è stata
suddivisa l’ontologia vengono quindi proposti scenari, esempi e domande di competenza, elencate le entità più
rilevanti e proposti sia un allineamento con le ontologie esistenti, sia alcune necessarie integrazioni.
Keyword: ontologie, digital art history, mercato dell’arte, rappresentazione della conoscenza,
web semantico


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       Introduction

Among the many fields of research related to art history, art market studies is one that has seen
a major increase in recent years.
After focusing on the study of artists' personalities, contributing to the reconstruction of their
catalogues, and defining a shared art historical canon, scholars have recently returned the history
of works as material objects to the center of their interest. The movements of paintings,
sculptures, and other artistic items; their confluence in different collections that reflect specific
tastes; the dispersal and recomposition of cultural heritages in areas different from those in which
they were produced; the commercial strategies of the agents who facilitated this network of trade:
all these have become increasingly investigated topics. Many initiatives and interdisciplinary
projects about the art market and history of collecting were promoted by research centers and a
rich literature was produced, including specialized journals and entire book series. Among them,
at least the Zentralarchiv für deutsche und internationale Kunstmarktforschung (ZADIK); the
Forum Kunst und Markt, with its Journal for Art Market Studies; the Project for the Study of collecting
and Provenance of the Getty Research institute; the Antique dealers project of the University of Leeds,
are worth mentioning (for an overview, [3]). Moreover, the Bloomsbury Art Markets database,
including numerous entries about protagonists of the international art market since 1900, has
been recently launched with the aim of becoming a reference point for scholars in the field
(Bloomsbury n.d.).
The Fondazione Federico Zeri has actively participated in this debate, with a focus on the art
market in Italy in the 19th and 20th centuries. In addition to promoting conferences and
publications ([1]), it has recently supported two research grants aimed at collecting unpublished
information on dealers and collectors linked to the archive and the personal history of its
founder.
As is well known, the Fondazione preserves the documentary collections of Federico Zeri (1921-
1998), who was one of the leading art historians of the last century and an infallible connoisseur.
They comprise a photo archive composed by 290,000 photographs of artworks and monuments,
a library made of 46,000 books, and a collection of 37,000 auction catalogues, the largest of its
kind in Italy. The scholar has used these resources as indispensable working tools to carry out
his work as an independent scholar. In his career, he has been an adviser to dozens of art
galleries, antiquaries, collectors, and auction houses, guiding them in their respective purchases
and sales on the market. This activity is reflected in the handwritten annotations on the
photographs and volumes. Among them, more than 500 names of individuals active in the
market during the last two centuries were retrieved. How to systematize, normalize, and deepen
data about these subjects was one of the main aspects of the cataloging project of the
documentary collections ([17]).
Despite the studies and resources cited above, we realized how difficult it was to retrieve
complete and detailed information about these figures using traditional art historical research
methodologies. The nature of the art market entails a number of resistances to the dissemination
of data on buyers, dealers, and sale prices of works. The lack of reliable data about transactions
has proven to be the first in a series of aspects that characterize this domain and distinguish it
from other business sectors.
First, those of antique dealers are often family-run businesses in which grandparents, children
and grandchildren frequently use the same names: this results in extreme difficulty in figuring
out to which different individuals certain information refers. On the other hand, the corporate
name of a given gallery may change several times over time, for example, as a result of the

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opening of new branches or the establishment of more or less stable joint ventures with other
partners. Alongside the figure of the dealer revolves a wide network of advisers and
collaborators. These include restorers, informants, and scholars with expertise in certain areas
of art historical production, or in specific periods and styles, whom antiquarians or auction
houses use to determine the quality and value of particular pieces. They may assist in writing files
and catalogues, organizing sales, promoting dealers to collectors or museum directors. Being
able to reconstruct and represent this network can contribute significantly to understanding the
contexts and mechanisms of the art market.
Another typical aspect concerns what appears to be the very core of the domain: the transaction.
The price of the works offered for sale depends not on their intrinsic characteristics but on a
number of external elements that concur to determining their commercial value: first of all, on
the attributions made by more or less authoritative art historians that accompany the pieces; then
on their collecting history and state of preservation; again, on the fortune that a given style or
artist comes to have at a given historical moment, in parallel with the evolution of fashion and
taste, and so on.
Given the difficulty of accessing the antiquarians' personal archives, the study of the art market
involves the use of other, sometimes non-canonical sources: trade guides, narrative and
autobiographical texts, commercial magazines of the time, but, above all, the photographs of the
works put up for sale initially addressed to advisors and potential clients, which have since been
deposited in the photographic collections of scholars or art-historical institutions ([3]). It is no
coincidence that it was from the cataloguing projects of these archives that the need emerged to
investigate and systematize information on the subject.
The last type of source to be considered are the direct testimonies of market agents and their
successors (children, grandchildren, colleagues etc.). The research promoted by the Fondazione
involves extensive use of direct interviews and oral testimonies given by these individuals, which
researchers are collecting and transcribing.
The ontology presented here in its guidelines, and currently under construction, aims to
represent these and other specific aspects of the art market domain, and aspires to become a
reference model for anyone interested in structuring, enhancing, and integrating scholarly data
related to this field.



       State of the art

The construction of an ontology for the art market domain requires at first a recognition of this
multifaceted research field, in order to identify a selection of relevant projects concerning the
description of objects, agents, and transactions typical of this domain.
As the project mainly deals with cultural heritage data, the principal reference ontology is
CIDOC-CRM, the conceptual model proposed by ICOM which is a standard for the semantic
description of pieces of information in this domain. One of the main peculiarities of this project
is the relevance of the notion of event. Indeed, this approach permits “a more accurate view of
the past or current life history of a cultural object, […] interprets more effectively history and
especially heterogeneous and complex information resources that […] need to be linked and
interpreted in order to capture knowledge” ([9]: 1).
In addition, this class also permits to model one of the core elements of the art market, which is
the economic transaction. The solution proposed by CIDOC-CRM puts forward a streamlined
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definition of this phenomenon, which is mainly corresponding to a change either in the
possession or in the custody of a crm:E18_Physical_Thing instance. Since this model already
defines all the main pieces of information usually used by researchers in the art historical domain,
further economic factors described by other ontologies and conceptual models (e.g. see [15])
will be thus not considered.
In this perspective, our final ontology will be centered on this class as well, which will enable us
to link different modules conceived for the description objects, documents, agents. While the
first two can still be defined by CIDOC-CRM (specifically through the class crm:E18), the
internal dynamics within art galleries are difficult to describe with the ICOM standard model.
Consequently, an integration with another module, focused on the structure of organizations,
has been deemed necessary.
Reynolds ([22]) already proposed The Organization Ontology (Org), which is an effective tool to
describe the roles and position within a company, the changes in its major characteristics, as well
as modification in the personnel. Moreover, this model shares relevant features with CIDOC-
CRM class hierarchy. In particular, the class org:ChangeEvent, through which modifications of
the studied company can be asserted, can be interpreted as a better specification of
crm:E5_Event. Besides, Org integrates a widely used pattern in modelling the agent, which is
actually an imported class from FOAF (http://xmlns.com/foaf/0.1/) and which can be aligned
with crm:E39_Actor. Org main class, org:Organization, is defined as a subclass of foaf:Agent,
on the same hierarchical level as the other two subclasses foaf:Person and foaf:Group.
The enhancement of CIDOC-CRM model for the description of sources and evidences has been
instead already suggested by the project Zeri&LODE, which serialized in linked open data the
metadata of the photographs of the Zeri Photo Archive related to the artworks of the Italian
Cinquecento. Indeed, this initiative translated into two complete ontologies the Scheda F (F
Entry, for photographs) and Scheda OA (OA Entry, for artworks) defined by Italian ICCD
(Central Institute for Cataloging and Documentation of the Ministry of Culture), thanks to which
it is also possible to express main bibliography connected to the catalogued item. CiTO (Peroni
and Shotton 2012) was hence reused to quote sources to reconstruct the attribution of an
artwork, while HiCO ([8]) was imported “to describe the interpretation process relative to
subjective attributions” ([7]: 4).
As the final ontology will be asked to re-use some of these existing modules, this brief overview
serves as premise for the analysis of more specific projects, assessing both the degree of
interoperability with community standards and the ability of modelling relevant information for
art historical research. For instance, an interesting endeavor in modelling the art market has been
done by Filipiak et al. ([11]), which emphasizes mainly the economic characteristics of an auction
in the art market. The quoted conference paper displays two main excerpts of the ontology,
reported in Figura 1and Figura 2.




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           Figura 1. Excerpt of the art auction ontology, sales data (from Filipiak et al. 2016)




         Figura 2. Excerpt of the art auction ontology, artwork data (from Filipiak et al. 2016)

The former fragment is particularly relevant as it stresses the importance of not directly linking
the artwork to the sales, rather the model relies on the intermediate class of lot, the “central
entity” of the shown part of the ontology, in which “a particular item is offered for sale” ([11]:
6). Nonetheless, the project seems to consider only a specific situation, consisting of artworks
by a known author (see Figura 2), omitting other crucial practices of this domain (such as
evaluations or expertises), which are instead important in the definition of the exchange value
of the single object.
The current state of the art hence now lacks a consistent and comprehensive data model which
enables the interaction between current standard modules used to describe objects, event, and
agents. On top of that, the new ontology will be indeed asked to define both relevant practices
of the art historical domain and to state relevant archival and bibliographical sources, in order
to support and streamline future researches of this sector.



       Towards the Art Market Ontology

       Methodology
As said, the “Art Market Ontology” is intended to build up meaningful relationships among
different elements of the art market and the art-historical scholarships. Such a broad ontology
hence needs to be subdivided into minor modules; in particular, three main domains have been
defined.
The first one is focused on the agent (i.e., the art dealer) and describes the possible relations
connecting a single person to an organization (e.g., the art gallery or the auction house). The
second module is focused instead on the artwork and the agent in the context of the transaction:
the various kinds of economic exchanges are taken into consideration and special attention has
been paid to the analysis of value attribution processes (authorship attribution, expertise, and
value proposition). Lastly, the third module scrutinizes the documentary sources on which art

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historians rely to reconstruct the activity of art dealers. As discussed in the following paragraphs,
they consist of either single objects or entire curated holdings, such as archives.
The following ontology will be developed relying on SAMOD methodology ([19]):




                              Figura 3. SAMOD Methodology after Peroni ([19])

Indeed, the acronym SAMOD stands for Simplified Agile Methodology for Ontology Development and
is based on an iterative process in which a “domain expert” (DE) and “ontology engineer” (OE)
collaborate to define motivating scenarios, which are small problems defined in natural language
and associated to a set of informal and likely examples. After this first step, competency
questions are formulated. On this basis, the OE develops a standalone modelet and refractors it
to check “formal” and “rhetorical” requirements, that is mainly to verify the absence of
inconsistencies and to compare the solutions of the SPARQL competency questions with the
expected results.1
Due to time constraints, the SAMOD methodology has been slightly revised, as at first the
motivating scenarios and the competency questions have been defined with the DEs for all the
foreseen iterations, in order to collect in advance all the necessary material for the construction
of the single modelet. The following paper will hence propose a preliminary analysis, scrutinizing
the collected materials: in particular, this essay is aimed at both identify in the possibilities of a
direct reuse of existing ontologies, especially CIDOC-CRM ([4]), and at proposing the necessary
integrations.
These reflections will serve as guidelines in the proper construction of the ontology, whose
responsibility lies entirely with the OE. Indeed, also the remaining steps of the SAMOD
methodology are to be implemented. Firstly, the modelets will be drawn with the software yEd2
using the graphical framework Graffoo. 3 The model will be later converted into .owl file with the


    1   See SAMOD guidelines ([19]) for a more detailed description of this methodology.
    2   yWorks. yEd. https://www.yworks.com/products/yed.
    3   Peroni, Silvio. Graffoo. https://essepuntato.it/graffoo/. See Falco et al. ([10]).
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tool Ditto4 and populated in Protégé.5 Fulfilment of formal requirement will be checked both in
this software, with the reasoner HermiT,6 and with OntOlogy Pittfall Scanner (OOPS!).7 After
populating the ontology with the example dataset, the plug-in SPARQL Query8 installed in Protégé
will be used to verify the correctness of the answers to SPARQL-format competency questions.
On the contrary, in the test case phase, rhetorical requirements of model, data, and query tests
(bag of test cases) will be checked manually. Table 1 sums up the used design tools, associating
them with the corresponding step of the SAMOD methodology:
 SAMOD Step                                                            Tool
 Building of the modelet
        •     Graphical representation                                 Graffoo

        •     OWL serialization                                        DITTO

 Model test, formal requirements                                       Protégé – HermiT Reasoner
                                                                       OOPS!
 Building of the dataset according to the developed modelet            Protégé
 Data test, formal requirements                                        Protégé – HermiT Reasoner
 Query test, formal requirements                                       Protégé – SPARQL Query
         Table 1 Tools for ontology design compared with the various stages foreseen by SAMOD

As foreseen by SAMOD methodology, modelet merging and milestones releasing will be
admissible only in case the requirements stated by the bag of test cases are met.

            Modules
As mentioned, the domain will be subdivided into three core modules, which will be iteratively
described through sets of motivating scenarios, relevant examples 9 and competency questions.
These structures will be presented and analyzed in the following paragraphs and will be
commented on using existing ontologies as references.




    4   Peroni, Silvio. DITTO. https://essepuntato.it/ditto/. See Gangemi and Peroni ([14]).
    5Stanford University, School of Medicine, Stanford Center for Biomedical Informatics Research.
    Protégé. https://protege.stanford.edu/.
    6Oxford University, Department of Computer Science, Data and Knowledge Group - Knowledge
    Representation and Reasoning. HermiT OWL Reasoner. http://www.hermit-reasoner.com/.
    Reference version: HermiT 1.4.3.456.
    7Ontology Engineering Group. OntOlogy Pitfall Scanner. https://oops.linkeddata.es/. See Poveda-
    Villalón, Gómez-Pérez, and Suárez-Figueroa ([21]).
    8   Redmond, Timothy. SPARQL Query. https://protegewiki.stanford.edu/wiki/SPARQL_Query.
    9 The examples enable to analyze the reference scenarios through practical case studies. Nonetheless,
    they are fictious and any reference to people, organizations and events is to be considered purely
    coincidental.
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       Agents
This module is intended to describe the art dealer activity when carried out both by a private
individual and by a complex and structured organization, such as an auction house. The first
motivating scenario hence provides a first overview:
 1.1 General overview of the main agents in the art market
 Motivating scenario       An art dealer activity can be carried out by either a person, specialized
                           in a particular discipline, or an organization, which can be of various
                           types, including an auction house, and has a person in charge
                           (managing director). There may be people and organizations that do
                           not carry out an art dealer activity but are nevertheless involved in
                           the cultural industry.
 Examples                       1.   SR, specialized in Mannerist painting, is in charge of the
                                     auction house “Antichità”.
                                2.   MF, specialized in Baroque sculpture, oversees the art
                                     gallery “Beaux Arts”.
                                3.   BV is the director of “Universo mostre”, an organization
                                     which cannot be considered properly as an art dealer, albeit
                                     it operates in the artistic sector.
 Competency                     1.   Who is the managing director of the auction house
 questions                           “Antichità”? (SR)
                                2.   In which field is the managing director of “Beaux Arts”
                                     specialized? (Baroque sculpture)
                                3.   Are there organizations which are not art dealers? (Yes,
                                     BV’s “Universo mostre”)
    Table 2. First iteration of the module "Agents": motivating scenario, examples, and competency
                                               questions

This first presentation already permits us to identify the most relevant entities and properties
involved. The scenario indeed already paves the way to a possible alignment with both CIDOC-
CRM (from now on, crm:) and Org: the main class, which gives the name to the entire module,
is indeed “Agent”, which is to be modeled as superclass of both “Person” and “Organization”.
Albeit the definition of these entities might be intuitive, due to the typology of actors involved
in the art market, it is advisable that the last class would be associated with org:Organization,
consequently with a narrower semantics than crm:E74_Group. Indeed, it will not comprise
unstructured and unorganized gatherings of human individuals.
Moreover, the requirements stated by the scenario and the competency questions indicate as
necessary a more detailed description of the class “Organization”. Even though the majority of
its subclasses will be introduced in the following scenarios, it is still possible to introduce
“ArtDealerOrganization”, which is in turn superclass of “AuctionHouse”. If the latter is already
defined by the ontology developed by Filipiak (see supra), existing models seem to provide either
semantically broader and narrower concept, but lack of a specific class to define agents (or
“actors”, as formulated by CIDOC-CRM) who play an active role in exchange, conservation,
creation and restoration of the objects who are destined to the art market.
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On the other hand, the involvement in the art market cannot be a sufficient criterion to
differentiate also the entity “Person” in two subclasses. As a matter of fact, an organization is
founded with a specific scope, while an individual can be active in more than one domain and
not mandatorily at the same time. “Person” class instances’ activity should be hence considered
as a role and should not be defined by instantiating an individual of a specific subclass, rather it
could be inferred by the participation to specific events (see second module). The scenario
instead requests to better define the education and specialization of the single person: in this
case this domain of knowledge can be modeled as a separated class which can be aligned with
the FABIO (https://sparontologies.github.io/fabio/current/fabio.html) class (from now on,
fabio:) fabio:SubjectDiscipline. The definition of the role within the organization will instead be
analyzed in an ad hoc scenario (no. 1.4), devoted to the possible collaborations an art dealer may
establish during his activity.
The second and the third scenarios are instead focused on the creation, the modification, and
the cessation of the art dealer activity.
 1.2 Possible different organizations of an art-dealer company
 Motivating scenario       The company is defined by a foundation, which establishes the
                           involved actors, the name, the location, the date, and the type of
                           activity. Several companies may refer to the same family venture,
                           which indicates all business activities owned by the members of the
                           same family. The company may open new branches and laboratory.
 Examples                       1.   The art dealer ST, after opening the “Arti d'Urbe” gallery
                                     in Rome, Piazza delle Erbe, in 1949, opened a restoration
                                     laboratory in Rome, Piazza Navona, in 1956.
                                2.   The art dealer CP opened a second branch of the Galleria
                                     “Artimercato” in Florence in Via dei Fossi in 1977.
                                3.   LZ and PS founded a gallery together in Rome in 1980
                                     under the name “Arti libere”.
 Competency                     1.   Which activities did ST found? (“Arti d'Urbe”, 1949, Piazza
 questions                           delle Erbe, Rome; P.za Navona, Rome, ST, 1956)
                                2.   Which are all the business activities referable to the P.
                                     family? (“Artimercato”, n.a., Milan; n.a., 1977, Via dei
                                     Fossi, Florence)
                                3.   What are the activities in Rome between 1950 and 1985?
                                     (“Arti d'Urbe”, P.za delle Erbe, Rome, ST, 1949; n.a., P.za
                                     Navona, Rome, ST, 1956; “Arti Libere”, Roma, LZ and PS,
                                     n.a.)
   Table 3. Second iteration of the module "Agents": motivating scenario, examples, and competency
                                              questions

Compared to the previous one, this scenario is intended to describe the main relationships
between the single person and the art dealer organizations and its subclasses. On the one hand,
it describes a quite common dynamic in the art market domain, i.e., the presence of different
secondary activities (i.e., branches) which can refer to the same main organization. Among these,
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restoration laboratories also play a relevant role. For example, as analyzed by Mambelli in the
commercial venture of Sangiorgi ([18]), the presence of an ad hoc venue to restore artefacts and
create in-style reproductions was a crucial sector of his antiquarian activity. Existing conceptual
models, such as the Organization Ontology, are able to describe the hierarchical relationship
between two organizations thanks to org:hasSubOrganization (and the inverse,
org:subOrganizationOf), although a new class should be introduced to describe laboratory.
Being subclass of org:Organization and of crm:Group, the activity of restoration and production
does not need to be described in this model, rather it can be delegated to CIDOC-CRM, in
particular through the classes crm:E11_Modification and crm:E12_Production.
The distinction between different interrelated organizations lead to necessity to also describe the
geographical and chronological extent of the activity. This goal was pursued by the reuse and
the enrichment of the triple “org:Organization org:hasSite org:Site”. In the Organization
ontology, the site is associated with a physical location, defined by an address. Nonetheless, it is
often difficult to precisely reconstruct this piece of information for the organizations operating
in the art market, due to both a lack in the sources and the fact that the toponymies might change
considerably during decades. Consequently, the class Site should be associated with
crm:E53_Place. In addition, since this ontology is being thought for supporting scholars in the
analysis of the domain, it will be necessary to indicate the time interval during which a seat was
active, in order to facilitate historical reconstructions.
Comparing to the existing models, the main introduction is the concept of the familiar venture,
which encompasses all the agents, both of class Person and Organization, which belong to the
same family across generations. The definition of this high-level entity has been deemed
necessary as it has been noted that art dealer companies tend to be handed down through
generations of the same family: the importance of this class permits hence scholars to observe
and analyze diachronically the evolution of a familiar business, scrutinizing its main protagonists.
Lastly, while the definition of the name and of the business type can be respectively asserted by
rdfs:Literal (RDF 1.2 Schema, https://www.w3.org/TR/rdf12-schema/) and skos:Concept
(SKOS Simple Knowledge Organization System, https://www.w3.org/2004/02/skos/), as suggested
by Org, the modelling of the opening of the organization should be imported by CIDOC-CRM.
Indeed, it already describes this phenomenon through the class crm:E66_Formation and the
property crm:P95_has_formed. Similar remarks can be made also for the third iterations, which
is indeed focused on the events which characterize the life cycle of a company:
 1.3. Events in the life cycle of an art-dealer company
 Motivating scenario       The company can be changed by events (defined by a date and place),
                           such as a change of location and names. The end of a company
                           occurs by cessation of activity or by acquisition by another individual
                           or company.
 Examples                       1.   In 1910 the antiquarian RT was forced to close the gallery
                                     “Tesori” in Piazza Duomo, Florence, which has been
                                     active since 1870.
                                2.   The auction house owned by SD is bought by MB in 1915.
                                3.   LZ in 1920 changed the name of the business “Arti
                                     fiorentine”, active in Florence in Via dei Fossi since 1850,
                                     to “Les Arts de Paris” when it moved the company to Paris,
                                     Champs Élysées.
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 Competency                     1.   In which period was the RT’s organization “Tesori” active?
 questions                           (“Tesori”, 1870, 1910, Piazza Duomo, Florence)
                                2.   Who is the buyer of SD’s auction house? (MB, 1915)
                                3.   Which events modified ZF’s organization? (LZ, 1920, “Les
                                     Arts de Paris”, Paris, Champs Élysées)
    Table 4. Third iteration of the module "Agents": motivating scenario, examples, and competency
                                               questions

Following the event-based modeling which characterizes CIDOC-CRM, the scenario can be
summed up into two main classes, the first one describing the cessation of activity, while the
second one its modification. The former entity is already asserted by the standard ontology,
which, in a strict parallelism to crm:E66_Formation, also defines the class crm:E68_Dissolution
and the property crm:P99_dissolved. Nonetheless, this class is not able to fully express company
purchase: in this scenario, this event is considered a cessation of activity as it causes a change in
the reference familiar venture. As a matter of fact, the class crm:E8_Acquisition can be referred
only to instances of crm:E18_Physical_Thing due to the range restrictions of
P24_transferred_title_of. The new subclass, “CompanyPurchase”, will be hence connected to
the seller and the buyer to ad hoc properties: despite being disjoint by the class “Transaction” of
the module event, its set of properties is similar to this latter entity, which will be described in
detail when discussing scenario 2.1.
On the contrary, the change of the company cannot be defined by other CIDOC-CRM
subclasses: like E8, also crm:E9_Move and crm:E11_Modification can be referred exclusively
to crm:E18_Physicial_Thing instances. The Organization ontology, instead, defines this
phenomenon through a new class, which can be easily integrated in CIDOC-CRM as subclass
crm:E7_Activity (in the class hierarchy, it would be hence at the same depth of E66 and E68):
org:ChangeEvent. As shown In Figura 4, this entity connects through specific properties the
two individuals, which correspond to the two configurations of the company before and after
the modification.




     Figura 4: Modelling of org:ChangeEvent. Personal elaboration in Graffoo after Reynolds ([22])

Moreover, the Organization ontology provides fruitful guidelines for the description of the
collaboration within a company, which is the focus of the fourth iteration of the module:
 1.4. Professional roles and collaborations in the art market
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Motivating scenario      An art dealer company relies on various professional roles, covered
                         by an individual or another society, with whom it forges
                         collaboration links defined by a time interval and functional to an
                         event, such as the creation of an object.
                         In addition to the managing director (they can also be more), the
                         main roles are (but not limited to) the reference art historian
                         consultant (who has a background in an art-historical domain; he
                         intervenes in attributions and catalogues), the restorer, the
                         photographer.
Examples                      1.   The antiquarian GT has several artworks without
                                   attribution. He therefore asks AB (a leading expert in the
                                   history of the miniature) to collaborate and study these
                                   works. This collaboration is occasional and lasts from 1980
                                   to 1982.
                              2.   In order to study the works properly, collaborator AB asks
                                   for photographs. Therefore, GT asks photographer AA,
                                   with whom he collaborated from 1960 until 1985, to take
                                   the photos.
                              3.   FR calls three experts with different skills to draw up a
                                   catalogue: GO, a scholar of Baroque sculpture, LA, a
                                   scholar of Mannerist painting, AB, a scholar of the history
                                   of the miniature. The photographer DD also worked on
                                   the catalogue (permanent collaboration).
                              4.   FZ, who had owned the company “Antichità fiorentine”
                                   since 1920, died in 1948. The business was continued by his
                                   son MZ until 1970. The company was founded by FZ's
                                   uncle AQ in 1910.
Competency                    1.   With whom did the art dealer GT collaborate between 1979
questions                          and 1985? (Art historian consultant, AB, 1980, 1982;
                                   photographer, AA, 1960, 1985)
                              2.   Which photographers are active between 1960 and 2000?
                                   (AA, 1960, 1985, GT; DD, n.a., n.a., FR)
                              3.   Who are the art historian consultants who worked with FR
                                   to prepare his catalog? (GO, Baroque sculpture; LA,
                                   Mannerist painting; AB, History of the miniature)
                              4.   Who are the directors of “Antichità fiorentine”? In which
                                   period were they active? (AQ, 1910, 1920; FZ, 1920, 1948;
                                   MZ, 1948, 1970)
 Table 5. Fourth iteration of the module "Agents": motivating scenario, examples, and competency
                                            questions



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As a matter of fact, CIDOC-CRM does not provide a specific class to describe the collaborations
between two actors, rather it permits to instantiate as event its beginning (crm:E85_Joining) and
its end (crm:E86_Leaving). Moreover, apart from crm:E55_Type, the semantic to express the
different role is not exhaustive. On the other hand, Org provides several classes to model this
domain: as stated by the documentation ([22]), each collaboration is defined as in Figura 5:




 Figura 5: Modelling of the collaboration in the Organization Ontology. Personal elaboration in Graffoo
                                           after Reynolds ([22])

The main classes (Membership, OrganizationalCollaboration, Post, and Role) are defined as
follows ([22]):
    •     org:Membership: “Indicates the nature of an Agent's membership of an organization”.
    •     org:OrganizationalCollaboration: “A collaboration between two or more
          Organizations such as a project. It meets the criteria for being an Organization in that it
          has an identity and defining purpose independent of its particular members but is
          neither a formally recognized legal entity nor a sub-unit within some larger
          organization. Might typically have a shorter lifetime than the Organizations within it,
          but not necessarily”.
    •     org:Post: “A Post represents some position within an organization that exists
          independently of the person or persons filling it. Posts may be used to represent
          situations where a person is a member of an organization ex officio (…). A post can
          be held by multiple people and hence can be treated as [an] organization in its own
          right”.
    •     org:Role: “Denotes a role that a Person or other Agent can take in an organization.
          Instances of this class describe the abstract role; to denote a specific instance of a
          person playing that role in a specific organization use an instance of org:Membership”.
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Although it provides meaningful suggestions, when applied to the historical reconstruction of
the art market, this solution is not completely convincing. Indeed, it combines professional
collaboration and membership to associations (which will be discussed in scenario 1.5),
differentiates between collaboration with organizations and with single individuals, and separates
in two level the covered role and the post inside a company. The data available for art dealer
organizations, in particular when they date back to several decades ago, does not always permit
to describe the situation in detail. The new ontology, whose main reference users are art
historians, should instead be able to define the domain in a more flexible and general approach.
To this end, a possible strategy would involve the creation of new ad hoc classes. The first one,
“Collaboration”, is conceptually related to org:Membership and refers to the fact that two agents
have stipulated any form of collaboration or partnership to maximize their own interests. This
can be translated also - but not mandatorily - into an employment contract. The two actors
involved should be subject of a specific property stating their participation in the collaboration.
This last property should be also differentiated into two sub-properties, which enable us to
express who has requested and who is providing the service. Following the class hierarchy of
Org, this entity should not be defined as subclass of events and should relate to a definition of
the role, which should be expressed in turn through a controlled vocabulary. With reference to
the instructions provided by the motivating scenario, a first nucleus of term shall include the
managing director (also mentioned in scenario 1.1), the art historian consultant (whose domain
of expertise may be rendered as in scenario 1.1), the restorer, and the photographer.
The class “Collaboration” should also state a time interval and could be associated to a specific
purpose, expressed as an individual of type “Event”. This solution is harmonized with the
reference CIDOC-CRM model: creation of catalogues and photographs, and modification (i.e.,
restoration) of artworks can be indeed stated by crm:E11_Modification and its subclasses (e. g.
crm:E12_Production). The activity of art historian consultant, in particular to what pertains
expertise and value attribution, can be instead rendered by the classes introduced in the second
module.
As mentioned, this new class does not completely cover the polysemy of org:Membership. The
participation of a member to an association should be hence described in a separate specific
scenario:
 1.5. Art dealer organization as member of association and participant to events
 Motivating scenario      A company may participate in several events (location, start date, end
                          date) organized by other agents or organize one at its own premises.
                          The main events are (but not limited to) fairs and exhibitions. Each
                          event can be described by a catalogue. The company can be a
                          member of an association that can promote events.
 Examples                      1.   In 2008, the “Arti belle” gallery organized an exhibition
                                    (2008-2009) in Rome. It also participates in the BIF event
                                    in Florence, organized by the association "AIT" in 2010
                               2.   The 'AIT' Association regularly promotes the
                                    “Artiromane” fair. SA, which has been a member of AIT
                                    from 1970 to 1985, participated in this event in 1982 and
                                    1984.



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                                3.   The 'Art' gallery is a member of the “AIT” organization
                                     from 1977 to 1988.
 Competency                     1.   To which event did “Arti Belle” art gallery participate?
 questions                           (“Arti Belle”, Roma, 2008, 2009; BIF, AIT, Firenze, 2010)
                                2.   Which organizations participated in the editions of the
                                     event “Arti Romane” between 1981 and 1985? (1982,
                                     Roma, AIT, SA; 1984, Roma, AIT, SA)
                                3.   Who are the members of the association “AIT”? (SA, 1970,
                                     1985; Art, 1977, 1988)
    Table 6. Fifth iteration of the module "Agents": motivating scenario, examples, and competency
                                               questions.

As anticipated, the scenario introduces a new subclass of Organization, i.e., “Association”,
identifying connections or cooperative agreements between agents which stipulated to defend
and pursue shared professional interests. The relationship between this class and its members
(of type Agent) is mediated by a new class, “Membership”, which states a specific time interval
(expressed through a data property) and has a more specific semantic comparing to
org:Membership as it excludes professional collaborations.
In addition, the scenario mentions other typology of events which characterize the activity of art
dealers, such as fairs and exhibitions, which can be specified as subclasses of crm:E5_Event.
Nonetheless, a necessary distinction should be made for recurrent events: antiquarian fairs
themselves can be included in this case, as each annual edition actually refers to the same series
(e.g., The European Fine Art Fair, TEFAF – Maastricht). This distinction in two separated levels
has been already tackled by DOLCE (http://ontologydesignpatterns.org/wiki/
Ontology:DOLCE+DnS_Ultralite, prefix, dul:), a foundational upper-level ontology (Gangemi
et al. 2002). The single recurrent event, besides being aligned with crm:E5_Event, corresponds
to dul:Event. On the contrary, the high-level series is actually already expressed by
dul:Collection, defined as “any container for entities that share one or more common properties”
(Gangemi n.d.). Other typologies of events which directly imply the economic exchange and the
definition of the monetary value are instead defined in a separate module, described in the
following paragraphs.
       Events
The specificity of the art market transactions will be instead treated in this second module.
Differently from other types of objects, cultural goods follow specific dynamics from an
economic perspective as they do not have an intrinsic economic value. The value (and
consequently the price) of each work of art is directly dependent on the discourse, who is
principally elaborated by intermediaries. These actors, which may correspond for instance to art
historians as author of expertises and attributions, are not directly involved in the economic
transaction. Rather, their role is to “translate and convert the symbolic value of artistic creations
into economic value through discourse that renders the goods intelligible, acceptable, and
valuable” ([16]: 6). Their activity massively impacts both consumers (buyers) and art dealers'
organizations, who cultural market theorists assigned to the class of producers, as they “have a
direct economic interest in the good exchanged in the market because they are involved in its
procurement” ([16]: 7). The two scenarios of this module will be hence aimed at summing up
the complexity of this domain.

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 2.1. Art dealer organization as member of association and participant to events
 Motivating scenario       An agent may have ownership and custody (they do not mandatorily
                           match) of an object or a set of artworks.
                           An agent's main activity is the transaction, which include buying (an
                           agent sells an asset in exchange for a sum of money; it changes
                           possession, custody or both), lending (an agent lends an asset in
                           exchange for a sum of money or free of charge, which changes only
                           custody), and donating (an agent gives an asset away free of charge:
                           in this case, both possession and custody change).
                           The asset is defined as a lot and may be a single work or a group of
                           works of art (sometimes even an entire collection). The transaction
                           is identified by at least two parties: one who transfers possession and
                           one who acquires it. A transaction may also have a facilitator.
 Examples                       1.   The antiquarian QC buys the work Sacra Conversazione from
                                     the private collector ST in 1978 for a sum of €10,000.
                                2.   On the occasion of the exhibition “Neoclassicism" (1980),
                                     the antiquarian PP lends a terracotta by Canova to the
                                     Museo Civico in Milan.
                                3.   Upon TC's death (1980), his heirs donated their collection
                                     to the Museo Civico in Florence.
                                4.   The museum Museo Civico di Belle Arti in Rome bought
                                     the painting Birth of Bacchus by Giulio Romano from the
                                     antiquarian RE in Florence, at the suggestion of the scholar
                                     TD
 Competency                     1.   When did QC buy the painting Sacra conversazione? (1978)
 questions
                                2.   Who are the clients of ST? (QC)
                                3.   Who is the last owner of the artworks exhibited at
                                     “Neoclassicismo”? (Terracotta by Canova, PP)
                                4.   Who participated in the acquisition of Romano’s Birth of
                                     Bacchus? (Museo Civico di Belle Arti in Rome, buyer; TD,
                                     facilitator; RE, seller)
    Table 7. First iteration of the module "Events": motivating scenario, examples, and competency
                                               questions

The central classes of this scenario are events subclasses and are related to CIDOC-CRM classes
crm:E8_Acquisition, its subclass crm:E96_Purchase which involves an exchange of a monetary
amount, and crm:E10_Transfer_of_Custody. These classes can be considered subclasses of a
broader entity “Transaction” and, as they are not disjoint, it is possible to propose the following
alignment with the classes mentioned in the scenario (“Purchase”, “Loan”, “Gift”):
    •    “Gift” is intersection of crm:E10 and crm:E8, but disjoint from crm:E96, as it does
         not foresee an exchange of a monetary amount;
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    •    “Loan” is a subclass of crm:E10;
    •    “Purchase” should be instead considered as subclass of the union of crm:E96 and
         crm:E10 (as stated by the scenario, transferal of ownership and of custody might not
         coincide).
To what pertains the definition of the price, CIDOC-CRM already provides the property
cm:P179_had_sales_price, with crm:E97_Monetary_Amount as range. However, the domain of
the property is restricted to crm:E96: as a result, the “Art Market Ontology” will introduce a
more general super-property “hasPrice”, stating as domain the union of “Purchase” and “Loan”,
since the scenario mentions that also leaning works of art may involve a monetary exchange.
The role of the involved actors can be more generically defined at the level of the new super-
class “Transaction” with three properties: “hasSurrender” (potential super-property of
crm:P23_transferred_title_from and crm:P28_custody_surrendered_by), “hasReceiver”
(potential super-property of crm:P22_transferred_title_to and crm:P29_custody_received_by)
and “hasFacilitator”, which permits to express the intermediation of a third agent in the
transaction. On the contrary the two properties crm:P24_transferred_title_of and
crm:P30_transferred_custody_of may not be grouped under a single super-property to underline
the difference between a change in the ownership and in the custody. As outlined in the
paragraph on the state of the art (Filipiak et al. 2016), they will associate a transaction (according
to their domain) with a “Lot” class, which will be hence considered subclass of
crm:E18_Physical_Thing. The use of crm:P46_is_composed_of will permit to describe the sold
object(s), either of type – again – crm:E18_Physical_Thing10 or crm:E78_Curated_Holding.
As stated above in the brief overview on the art market, these kinds of events are often preceded
by other ones, as described in the last scenario of this module:
 2.2. Art dealer organization as member of association and participant to events
 Motivating scenario       The peculiarity of the art market is the fact that the value of an
                           artwork cannot be deduced objectively but depends on multiple
                           external factors. In fact, an agent can value the work independently
                           or by relying on an expert. He reconstructs several characteristics of
                           the work of art. Among these, some important ones are the artefact's
                           authorship (attribution), state of preservation, collecting history
                           (understood as a series of possessions), bibliography.
                           Based on this analysis, an agent proposes a monetary value for the
                           object. Both the attribution and the value proposition can be re-
                           discussed over time by other attributive assignments: all these events
                           influence (without necessarily coinciding) the real price of the
                           transaction.
                           The asset may be subject to notification (usually not withdrawn but
                           may only be valid for a certain amount of time) by the State and this
                           affects the value of the asset.



    10Albeit the ontology primarily deals with artworks, the domains stated by crm:P46 will be
    maintained unchanged as historical collections may also contained instances of crm:E18 which are
    not man-made (hence, not product of a crm:E12_Production activity).
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 Examples                       1.   In 2001, the antiquarian PT calls the reference scholar SB
                                     to have him study a 17th century painting (San Rocco). He
                                     attributes the artwork to Guido Reni.
                                2.   In 2005 SB studies a Deposition attributed to Guido Reni:
                                     after some research he attributes it instead to
                                     Domenichino.
                                3.   The antiquarian SZ owns a painting by Tintoretto, whose
                                     value in 1980 was €15,000 because a previous appraisal
                                     showed it to be in a good state of conservation and the
                                     work is mentioned in the catalogue Le opere di Tintoretto.
                                4.   Based on the analysis of Tintoretto's canvas by the scholar
                                     ML, commissioned by SZ, it was discovered that the work
                                     was owned by Count F. SZ put it on sale in 1990 at the
                                     equivalent cost of 35,000€ and at 30,000€ in 1991.
                                5.   The work San Rocco by Guido Reni was notified in 2008 by
                                     the Italian State.
 Competency                     1.   Which artworks did SB study? (San Rocco, Guido Reni,
 questions                           2001; Deposizione, Domenichino, 2005)
                                2.   Which are the different value attributions of the canvas by
                                     Tintoretto? (1980, 15000€; 1990, 35000€; 1991, 30000€)
                                3.   Are there artworks under notification? (Yes: San Rocco,
                                     2008, owned by PT)
   Table 8. Second iteration of the module "Events": motivating scenario, examples, and competency
                                              questions

The two main events mentioned in the scenario can be modeled as two separated subclasses of
crm:E13_Attribute_Assignment. As subclass of crm:E7_Activity and crm:E5_Event, the
professional collaboration and partnerships involved can be stated following the model defined
in scenario 1.4. The first entity, "Expertise", concerns the expertise made by the art historian
and is aimed at identifying author and previous owner, at diagnosing the conservation state, with
the support of different source. CIDOC-CRM already proposes a solution to states these
elements, using the combination of:


crm:E13_Attribute_Assignment crm:P11_had_participant crm:E39_Actor.
crm:E13_Attribute_Assignment         crm:P140_assigned_attribute_to
crm:E1_CRM_Entity.
crm:E13_Attribute_Assignment crm:P141_assigned crm:E1_CRM_Entity.
crm:E13_Attribute_Assignment     crm:P177_assigned_property_of_type
crm:E55_Type.




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The most relevant peculiarities of the “Expertise” have been already modeled by the HICO, the
Historical Context Ontology (Daquino and Tomasi 2015), which is centered on the class
hico:InterpretationAct, as shown in Fig 6:




                                  Figura 6: HICO Conceptual model

Defining     “Expertise”   as    subclass      of   both     hico:InterpretationAct    and
crm:E14_Condition_Assessment permits to state all the different attributes mentioned by the
scenario. Indeed, ownership and authorship can be defined as distinct
hico:hasInterpretationType (the documentation, https://marilenadaquino.github.io/hico/,
already provides on example of author attribution based on the dataset of Fondazione Zeri
Photo Archive) and the conservations status can be expressed as crm:P35_has_identified
crm:E3_Condition_State.
In           addition,           the          use           of           CITO          ontology
(https://sparontologies.github.io/cito/current/cito.html), whose properties do not contain
domain and range restrictions has been removed after v1.6 (Peroni and Shotton 2012, 40),
permits to state with several semantical nuances both supporting sources (here considered as
instances of crm:E24_Physical_Human-Made_Thing) and relationships between different
events of type of crm:E13 (in this model, both “Expertise” and “ValueAttribution”). This latter
use case expresses for instance agreements and disagreements among different agents studying
the same objects. Moreover, it also permits to express a causality nexus between “Expertise” and
“ValueAttribution”, the second subclass of E13 introduced by the scenario. On the basis of the
assessments made in the former event, a monetary evaluation of the work of art can be proposed.
Similarly to definition of the attributed author, the proposed price can be stated with another
sub-property of crm:P141, such as “hasProposedPrice”, with crm:E97_Monetary_Amount as
range.
Lastly, the scenario also introduces the possibility of having legal constraints on the event. With
reference to Italian legislative system, one of the most famous examples is the “notifica” (ex
d.lgs. 22 gennaio 2004, n. 42, c.d. Codice dei beni culturali e del paesaggio). This act recognizes the
value cultural, artistic, historical, or ethno-anthropological interest of cultural artefacts (included
collections, hence generically of crm:E18_Physical_Thing) and limits their circulation. CIDOC-
CRM already provides a framework to describe this phenomenon, i.e. crm:E30_Right. The
properties in which this class is involved permit to state limit on instances of class “Transaction”.
As:

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crm:E50_Right crm:P67_refers_to crm:E1_CRM_Entity.
crm:E7_Activity crm:P15_was_influenced_by crm:E1_CRM_Entity.

It would be indeed possible to assert the following axioms:


crm:E50_Right crm:P67_refers_to crm:E18_Physical_Thing.
:Transaction crm:P15_was_influenced_by crm:E50_Right.

       Sources
The last module of the “Art Market Ontology" pertains the use of sources for the historical
reconstruction of the activity of the main protagonists of the art market. It consists of a single
iteration as it is already possible to model sources thanks to existing ontologies. The scenario
will hence mention only the most frequently used documents to reconstruct this domain and
will pay attention to the most generic properties which associate a source with the event or the
agent they refer to.
 3.1. Sources for the historical reconstruction of the art market
 Motivating scenario      Objects may mainly (but not only) be bibliographic (comprising
                          various types, including catalogues) or archival item (such as, but not
                          limited to, account ledgers, receipts, letters, photos) and works of art;
                          they may be contained within a curated holding (library, archive,
                          including photo archive, or art collection; they may have extension
                          indications) which is identified by a current owner (an agent) and
                          which may in turn be contained by another holding.
                          These elements can be used as sources for events or agents: some of
                          them are precipitates of the agent's activity (primary source), while
                          others are the result of later studies (secondary source).
 Examples                      1.   The archival collection of the antiquarian GT, comprising
                                    600 photos and 300 letters from 1940 to 1990, is now
                                    owned by the SZ Foundation.
                               2.   The “Art Institute” research center owns KG's archive,
                                    which contains several primary sources, such as receipt
                                    #KG1950 from the sale of a predella by Gentile da
                                    Fabriano and a letter to SZ.
                               3.   There is also KG's autobiography My life, the unpublished
                                    manuscript of which is now in the possession of the heir
                                    FG
                               4.   There are also secondary sources on KG: the volume KG:
                                    An Ar Collectionist and the website KG on the web.
 Competency                    1.   Who is the owner of GT’s archive? (Foundation SZ)
 questions

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                                  2.   Which are the sources which can be used to reconstruct the
                                       life and the activity of KG? (KG’s archive, “Art Institute”;
                                       Receipt #KG1950, “Art Institute”; Letter to SZ, “Art
                                       Institute”; KG. My life, FG; KG: An Art Collectionist, n.a.; KG
                                       on the web, n.a.)
    Table 9. Main iteration of the module "Sources": motivating scenario, examples, and competency
                                               questions

Sources can be considered generically instances of the subclasses of crm:E18_Physical_Thing, in particular
two crm:E22_Human-Made_Object and crm:E78_Curated_Holding. Nonetheless, the scenario
introduces the need for further taxonomizing these super-classes. For instance, the latter one can be
subdivided into art collections, libraries, and archives (with the subclass concerning photo archives), in
parallelism with the standard classification of LAM institutions. They can be rendered as new specification
of crm:E78; moreover, they are also to be considered subclasses of fabio:WorkCollection, which enables
the interoperability with the F Entry ontology ([5]).
On the other hand, potential subclasses of crm:E22 could help in a more precise alignment.
Table 10 proposes a first solution to this challenge and lists the element into three hierarchical
levels (subclasses are identified by indentation). The root note, crm:E22, is subdivided into three
macro-categories which reflect the tripartition of the subclasses of crm:E78. The third level
mentions the most common sources on which scholars may rely for their historical
reconstructions: this list, therefore, is not conceived to be exhaustive, rather it reflects most
common academic praxes. In particular, “ArchivalItem” contains those objects which are usually
conservated by archives, such as letters and photographs. Moreover, the study of economic
exchanges is also possible thanks to account registers, on which an agent may have listed his
own belongings, and the receipts of the transactions (e.g., the records of the activity of
Kleinberger Galleries Inc. at Watson Library – The Metropolitan Museum of Art in New
York 11).
Similarly, bibliographical sources are grouped under the class “BibliographicItem”. It contains a
sole child class, catalog, which has been declared due to its undeniable importance art historical
analysis. Other kinds of publications can be instantiated relying on the rich taxonomy provided
by FABIO. The justification of this alignment is rooted in the solutions adopted during the
exposure in RDF of the F ([5]) and OA entry ([6]). The sole integration was the use of RICO
(Records in Contexts Ontology), the International Council of Archives standard ontology for
the description of “Archival Items”.
 crm:E22_Human-Made_Object                            fabio:AnalogItem
    Artwork                                              fabio:ArtisticWork
    ArchivalItem                                         rico:Instantiation
         AccountRegister
         Receipt
         Photo                                             fentry:Photograph



    11   See https://cdm16028.contentdm.oclc.org/digital/collection/p16028coll23/search.
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       Letter                                           fabio:Letter
    BibliographicItem
       Catalog                                        fabio:Catalog
                          Table 10. Alignment of the subclasses of crm:E22.

Another specificity of the domain is the need to use oral sources, such as interviews, to clarify
aspects not reported by documents or bibliography. The modelling of these sources cannot rely
exclusively on crm:E22, as they do not have per se “physical boundaries that separate them
completely in an objective way from other objects”. On the contrary, the re-use of the WEMI
conceptual model, translated into OWL by FABIO, allows to elude this problem thanks to the
use of fabio:Work class. Through the property fabio:hasPortrayal, this entity can be associated
to a specific instance of fabio:Item. This last class can be aligned with the crm:E22 to express
the possibility of conserving the interview on a support (either analog or digital), which can be
in turn included in a curated holding.
Lastly, the relationship between a source and the entity or the actors (i.e., with an owl:Thing
instance) it documents should be mediated by a third class, defined by HICO ontology (also
used in F and OA entry). An historical reconstruction can indeed be questioned, and it can be
contextualized in a specific and well determined chronotope: it therefore coincides with
hico:InterpretationAct. As shown in Figura 6, this class is domain of cito:cites and its
subproperties, such as cito:citesAsEvidence. The distinction between primary, which identifies
sources produced during the historical period they refer to, and secondary sources, relying on
primary ones, may be asserted through new sub-properties of this class. In addition, the class
hico:InterpretationAct can be aligned to frbr:Endeavour, which is in turn equivalent also to
frbr:Work. This permits to state the subject of the historical reconstructions through the follwing
axiom, where frbr:Subject refers to an arbitrary set of entities:

frbr:Work frbr:subject frbr:Subject




       Discussion

In the creation of the Art Market Ontology, we chose to bridge and integrate existing models,
such as that of Filipiak and colleagues or the Organization Ontology, which alone would not have
made it possible to describe such a multifaceted domain. Furthermore, the ontology is intended
to be interoperable with ICOM's standard model, CIDOC-CRM, and is also designed for future
full integration with the existing RDF datasets of the Zeri Foundation, as a systematic reuse of
the RDF models of the F and OA Entry has been made.
At this propaedeutical stage, some limitations can yet be identified. As a matter of fact, this
project provides a first general description of the art market, able to describe the most relevant
dynamics of this sector. Some minor peculiarities of a single event, of a particular agent or source
might hence be omitted in the serialization of the knowledge graph, as they were not foreseen
in the original motivating scenario. For each of the three modules into which it is subdivided,
one could certainly include other interactions and investigate more refined aspects and
relationships linking art market-related entities.

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The analysis of the research field started and remained closely linked to the contents of Federico
Zeri's archive and the database that resulted from its cataloguing. In order to test its validity, it
will certainly be necessary not only to take into consideration specific cases that the Foundation
has deepened over the years in monographic studies, but also to apply it to datasets built by
other research institutes active in the sector.
In this perspective, opening the discussion with renown art-historical research centers
mentioned in the Introduction, such as ZADIK, the Bloomsbury Digital Resources, the Getty
Research Institute or The International Art Market Studies Association would be for sure be
beneficial: comparing the different approaches and data structure of similar centers would allow
art-historians and ontology engineers to capture with greater precision the peculiarities of this
sector and could provide a number of further case studies for testing the model.
A further limitation concerns the specific nature of the sources used to explore the field of
research. Catalogs, archival documents, and oral histories can sometimes deliberately conceal or
distort certain details about business transactions. When collecting or using information about
art market dynamics, scholars often have to deal with ambiguous, partial, or incomplete data.
The ability to effectively express the possible inconsistencies, without this bias undermining the
validity of future research, remains one of the goals of the model, which has yet to be tested.



        Conclusions and further works

The article presents a preliminary analysis of an ongoing project aimed at defining an ontology
of the art market. It stems from the increasing attention received in recent years by art market
studies and from the long-standing research activities of the Federico Zeri Foundation.
Beginning with the evidence collected in the Archives and Photo Library, it has been engaged
for years in collecting information concerning mainly antiquarians active in Italy between the
nineteenth and twentieth centuries. It is therefore already in possession of very refined data on
some of the market protagonists that can offer a good sample to verify the correct functioning
of the model. At the same time, the Foundation has recently promoted two research grants for
scholars who are conducting a thorough analysis of aspects and protagonists of the market in
this same chronological and temporal span. This is producing a significant amount of ex-novo
data, coming from multiple sources, which must be recorded, systematized, and integrated with
other resources available on the web.
Besides providing a recognition of existing conceptual models, the paper reconstructs the
reference domain relying on the competency questions, examples and motivating scenarios
defined by the first iterations of the SAMOD Methodology. These materials laid the basis for
the identification of the most relevant entities and properties, which were modeled both through
systematic reuse of existing models and with the implementation of necessary integrations.
After the finalization of the ontology, the next steps include populating the Art Market Ontology
proposed with some case-tests part of the Fondazione Federico Zeri dataset, and establishing a
fruitful dialogue with other research institutions that are creating authority files or other digital
resources dedicated to this field.
The development of the ontology does not only satisfy the need to organize systematically the pieces of
information gathered thanks to traditional methodologies of art historical research. It will hopefully show
also how digital art history and knowledge organization practices can guide research even in the data
collection phase, leading to the production of rich, well-structured, and integrable dataset, so to offer new
strategies to further deepen the knowledge of the art market sector.
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       Acknowledgments

We would like to thank Prof Silvio Peroni and Prof Francesca Tomasi for their kind support
and guidance. Our gratitude goes also to the staff of the Fondazione Federico Zeri, especially
Marco Fossati, who collaborated as domain expert in the creation of the scenarios, of the
examples, and of the competency questions.



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