The concepts relative to Published Subjects and PSI have been developed initially with exclusive reference to topic maps, which need them for topic identity and merging. It has been considered lately that those concepts could be relevant, beyond topic maps, to whatever software, technology, system, language, document ... that need to handle internal representations of subjects. For such applications, the capacity to identify abstract, non-adressable subjects (concepts, classes ...) independently of any specific resource that represent, name, describe or document them, and of any specific implementation, is critical.

Among such subject-oriented applications can figure singularly those aiming at interoperability of ontologies. What are the subjects represented by those two classes in those two different ontologies ? Are those subjects equivalent? How could I assert such an equivalence? Those questions are similar to the one dealing with subject identity in topic maps - How do I know that two topics in two topic maps have the same subject?

The notion of PSIs as binding points for definition of subjects, using URIs as identifiers, is therefore relevant for interoperability of topic maps with each other, interoperability of ontologies with each other, and interoperability of ontologies with topic maps as well.

The W3C Working Draft "Requirements for a Web Ontology Language" expresses that requirement at: http://www.w3.org/TR/webont-req/#section-requirements

"Unambiguous term referencing with URIs :
Two terms in different ontologies must have distinct absolute identifiers (although they may have identical relative identifiers). It must be possible to uniquely identify a term in an ontology using a URI reference."

1.2 OASIS - W3C coordination framework

The proposed liaison between W3C WebOnt and OASIS PubSubj Working Groups is to consider in the general framework of recent efforts of coordination between OASIS and W3C. This coordination effort is one among OASIS various initiatives having the common goal of helping standards organizations and working groups to exchange information, cooperate whenever possible, avoid redundant efforts on overlapping domains, work towards interoperability of specifications and languages, and make their recommendations and specifications easily available and understandable to industry users. Among others:

-- OASIS adhesion to the Memorandum of Understanding (MoU) on Electronic Business.
http://www.oasis-open.org/news/oasis_news_02_11_02.shtml
-- The first Interoperability Summit in Orlando (December 2001)
http://www.oasis-open.org/news/oasis_news_11_20_01.shtml
-- The initiative for a Standards Registry
http://lists.oasis-open.org/archives/stdsreg/

2. Agenda Proposal

The WebOnt - PubSubj liaison should aim at

• Definition of common concepts, terminology and use cases.
• Recommended ways to make terms of an ontology available as PSIs.
• Recommended use of PSIs in the definition of an ontology.