In March 2003, the OMG issued an Ontology Definition Metamodel RFP
asking for propositions of extensions to
in order to permit UML users to create/import/export ontologies (especially
OWL ontologies) and hence
represent and share various kinds of knowledge.
[Note added in February 2005. The four submissions that have been made to this RFP have now been merged and have led to other documents (e.g., this comparison of UML and OWL). As one can expect, these documents have the content/approach of classic UML-related documentation which, in my opinion, is rather inadequate (irrelevant and uselessly complex) for describing or guiding "knowledge" modelling (as opposed to data modelling).]
As a first step to answer this RFP, Kerry Raymond (ex DSTC, now QUT) and I have created KRM, a MOF2 metamodel derived from the WebKB-2 data model which itself is an extension and normalization of the Conceptual Graph model. The WebKB-2 model and notations are of a higher-level than other models and knowledge representation notations (e.g. FOPC-oriented notations like KIF, frame-based notations like Frame-Logics, and database-oriented notations like RDF/XML) and hence ease knowledge representation, sharing and exploitation (inferencing).
A second step is to explain how UML and its notations can be extended to cover a
large range of knowledge representation cases, and how it relates to other
languages (models plus notations). I have done this by
comparing these languages according to a range
of knowledge representation features.
Click here for an ontology example extracted from the OWL guide and corrected.
In addition to language ontologies and notations, we also propose a general content ontology composed of a merge of various top-level ontologies and an extension and correction of the WordNet natural language ontology (see this article for details). Some schemas have been associated to some of the top-level categories (many more will be added). WordNet categories have been re-used and specialized in various examples/applications.
For scalability and knowledge use and re-use purposes, some ways to represent knowledge are better than others. For now, click on on the following links: lexical recommendations, logical/semantic and ontological recommendations.
Finally, knowledge sharing involves protocols for editing a shared KB, or techniques to merge independently developped ontologies (and then KBs). WebKB-2 has some shared KB edition protocols.
History of KRM
Examples 1 Examples 2