Ontolog Forum

Ontology Summit 2008 Communique Draft Review - "Ontology of Ontologies" Breakout Group

Ref: OntologySummit2008_Communique/Draft

The Team:


Ontology Summit 2008 - Metadata for Ontologies

1. Purpose of the Ontology Metadata

The community agrees that it not sufficient for the OOR just to store ontologies but that metadata for ontologies is necessary to support the sharing and reuse of ontologies within the repository.

The metadata should allow users to

- determine whether an ontology is suitable for a user purpose;

- capture the design rationales that underlie the ontology;

- find information about author, author credentials, and source of ontology reference material

- retrieve ontologies for use in domain applications;

- retrieve ontologies to be integrated with other user ontologies;

- retrieve ontologies that will be extended to create new user ontologies;

- determine whether or not an ontology can be integrated with user ontologies;

- determine whether a set of ontologies retrieved from the repository can be used together;

- determine whether an ontology in the repository can be partially shared.

The discussions surrounding the Ontology Summit 2007 should be the basis for the metadata for ontologies.

There should be policies for creation and modification of metadata and documentation of ontologies and the management of the persistence and sustainability of ontologies.

Users (including end-users, ontology and repository developers, subject matter experts, stakeholders) should participate in the collaborative ontology development life cycle and decisions regarding what metadata is suitable for ontologies in the repository.

We can consider logical metadata (logical properties of the ontology independent of any implementation or engineering artefact) and engineering metadata (properties of the ontology as considered as an engineering artefact).

2. Logical Metadata

The first logical property is to identify the language used to specify the ontology.

The report "Evaluating Reasoning Systems" contains a classification of formal languages used to specify ontologies. A formal language has a syntax (logical symbols together with a formally specified grammar) and a model theory (which specifies the conditions under which expressions in the language can be given particular truth assignments).

A formalizable language has a syntax, although it does not have a model theory. Examples of such approaches include Topic Maps and folksonomies (which are writen in XML)and ISO 15926 (which is written in EXPRESS).

Finally, some ontologies are only specified in natural language, including Wordnet , taxonomies, and thesauri.

2.2 Modularity

A second property of ontologies is based on modularity -- is a particular ontology a monolithic set of axioms, or is it composed of a set of smaller modules? Furthermore, is each module considered to be a separate ontology within the repository? If not, what are the relationships between the modules and which modules of an ontology can be used separately?

For example, the Process Specification Language (PSL, consists of a set of modules which are extensions of a common core theory PSL-Core. Metadata for each module specifies which other modules must also be included when using the module.

2.3 Relationships between ontologies

We can also specify various logical relationships between ontologies within the repository, including mutual consistency, extension, and entailment, and semantic mappings.

3. Engineering Metadata

In addition to the logical metadata for ontologies, we need to specify metadata for ontologies as considered as engineering artefacts. This includes

- provenance

- versioning

- existing applications of the ontology (e.g. interoperability, search, decision support)

- domain-specificity (e.g. biology, supply chain management, manufacturing

4. Conclusions

The Ontology Metadata Vocabulary (OMV), Dublin Core, ISO 11179, ISO 19763, and other existing approaches to provenance and versioning metadata are all candidates for aspects of the metadata for ontologies in the OOR.

We strongly urge an empirical approach to the identification and evaluation of ontology metadata. We should begin by collecting ontologies from Summit participants, and test out the different proposals for metadata on these ontologies. We should also develop use-case scenarios that will motivate the use of the metadata with these ontologies and help establish best practices. We especially challenge the participants in the UpperOntologySummit to create a prototype of the OOR that includes the upper ontologies.


Hayes, P. (1996) A Catalog of Temporal Theories, Technical Report UIUC-BI-AI-96-01, University of Illinois at Urbana-Champaign.

Bock, C., Gruninger, M., Libes, D., Lubell, J., Subrahamian, E. (2006) Evaluating Reasoning Systems, NISTIR 7310, National Institute of Standards and Technology.

Slides from the Evan Wallace presentation of 3/27 - see

Slides from the Elisa Kendall presentation of 4/10 - (includes additional metadata/provenance requirements)

Summary slides from Evan Wallace and Elisa Kendall - see

W3C vocabulary management draft -

OMG RFP which contains some rationale that may be helpful -

McGuinness, D.L. <,D..papers.html>;

Ding, L. <,L..papers.html>;

Pinheiro da Silva, P. <,P..papers.html>;

Chang, C <,C..papers.html>. PML 2: A Modular Explanation Interlingua. Proceedings of the 2007 Workshop on Explanation-aware Computing (ExaCt-2007), Vancouver, Canada, July 22-23, 2007.


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