ArCo (Architecture of Knowledge) is a collaborative project that involves the institute of the Italian Ministry of Cultural Heritage ICCD (Institute of Catalogue and Documentation) and the Institute of Cognitive Sciences and Technologies of CNR (Italian National Research Council). ArCo aims at modelling the wide domain of Italian cultural heritage for two main purposes: (i) building a network of ontologies, compatible and aligned whenever possible with existing ontologies, that can be used as a de facto standard for representing cultural heritage data; (ii) publishing ICCD data as LOD: about 800.000 publishable files stored in the ICCD General Catalogue database. In this paper, we present ArCo structure, design methods and tools, its growing community, and we delineate its importance, quality, and impact in using semantic technologies in the fruition of Cultural Heritage.
The cultural heritage domain has an intrinsic complexity, due to the high number of different types of cultural properties that a cataloguer may record, e.g. anthropological material, coin, park, painting, traditional music. They have a lot of shared information types (e.g. location, bibliography, dating), but also many peculiar characteristics (e.g. staircases and floors in a building). Moreover, their description may be very detailed: for a cataloguer is possible to gather information about measurements, exhibitions, documentation, authorship, inventories, relations between cultural properties, and so forth.
There are many projects and models developed in the context of cultural heritage (CH), to model, publish and
connect data on the web: CIDOC-CRM [
To build ArCo, we directly reuse classes and properties from the core (roles, agents, locations) modules of OntoPiA
[
In the development of the project, we followed the principles of eXtreme Design (XD) [
During the project initiation and scoping, domain experts shared with the ontology engineers’ team their knowledge of
the domain, providing guidelines and data model regulations for interpreting their data. A generic timeline and a release
plan with priorities were defined. As recommended, we worked in tight collaboration with our main “customer”, i.e. the
ICCD. However, given that the ICCD data will be openly published and have high potential for reuse by several other
stakeholders, we decided to interact with some representative of them since the very beginning of the process. In addition
to domain experts, other agents, such as companies, were involved in the definition of ontology requirements, initially
expressed in the form of user stories. The same requirements are reused in the ontology testing phase. Extending XD,
four selected companies were also included in an “Early Adoption Program” (EAP) that worked with the incremental
unstable releases of ArCo ontologies and data to test them for e.g. publishing their data according to ArCo ontologies,
linking their data to ArCo. The EAP members and all the other interested stakeholders created an active community that
interacts by means of a dedicated mailing-list [
Pattern-based ontology design plays a central role [
Since XD is iterative and incremental, ArCo ontology modules and ICCD data are periodically published as unstable releases: this allows us to involve customers and stakeholders in giving us continuous feedback on modeling and testing activities, and to detect new emerging requirements at early stage. 4 4.1
ArCo release consists of a docker container, available on GitHub [
ArCo knowledge graph is also available on the MiBAC official portal [
ArCo ontology network consists of seven ontology modules connected by owl:imports axioms. In Fig. 2, blue circles depict ArCo modules; the green circle indicates directly reused ontologies; the orange circle indicates indirectly reused and aligned ontologies. The network base namespace is https://w3id.org/arco/ontology/, and each module has its own namespace (e.g. https://w3id.org/arco/ontology/core/).
The arco module [
More specific types of cultural properties are defined
as :DemoEthnoAnthropologicalHeritage, :ArchaeologicalProperty, :ArchitecturalOrLandscapeHeri
tage, :HistoricOrArtisticProperty, :MusicHeritage, :NaturalHeritage, :NumismaticProperty, :Pho
tographicHeritage, :ScientificOrTechnologicalHeritage, :HistoricOrArtisticProperty (see the
diagram [
The core module [
The catalogue module [
The location module [
The denotative description module [
The context description module [
The cultural events module [
ArCo knowledge graph currently counts: 7 ontology modules, 327 classes, 379 object properties, 154 datatype properties,
395 restrictions. It counts about 170M triples and provides 24,008 owl:sameAs axioms linking to other datasets, such as
DBpedia [
Fig. 3 depicts an example of information of a painting with subject “Madonna con bambino” (tr.en. Madonna with child). On the left side, there is the XML data, expressed as string and stored in the ICCD General Catalogue, and on the right side there is the correspondent data in RDF format generated according to ArCo ontologies. In order to involve different stakeholders, we have organised a series of meetups associated with the ArCo releases. So far, we had 5 meetups, each attended by about 20 participants, and 1 webinar; we received 35 GitHub issues, and 27 people joined the mailing-list.
ArCo has a potentially very strong impact on both Cultural Heritage and Digital Humanities fields and related domains. At international level, ArCo ontologies allow to represent very detailed information on cultural heritage of many different types and ArCo data can be aligned to other CH data, ensuring a high reliable provenance. These ontology network and dataset will be used by institutions (such as museums, designated for cultural heritage preservation and enhancement), which intend to publish their data as LOD and/or link them to ArCo, as well as by companies and individual consumers (i.e. researchers, students, practitioners, citizens) that own and use CH data for different purposes.
Good examples, among others, of ArCo early adopters are: Synapta team [
Currently, an extraordinary amount of data on Italian cultural heritage, in the form of a LOD dataset, is available to anyone interested in querying, consulting and reusing them. ArCo ontologies are released and adopted directly by ICCD, which provides Italian regulations for cataloguing cultural properties. Therefore, ArCo has become, in LOD context, a standard for Italian cultural institutions aiming at creating Linked Data, according to ministerial regulations.
Since the valorization of cultural heritage through LOD enables sharing and reusing of cultural heritage data in an open interconnected and multi-domain knowledge base on the Web, we plan to improve ArCo ontology network and LOD. Future efforts will be directed to: (i) model peculiar information regarding natural heritage and information related to archive and library domains, (ii) improve entity-linking, and (iii) provide tooling support for CH data owners in order to encourage and simplify the adoption of ArCo and other ontologies by domain experts.