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Dagstuhl Seminar 9119

Terminological Logics

( May 06 – May 08, 1991 )

Please use the following short url to reference this page:

  • B. Nebel
  • C. Peltason
  • K. v. Luck



The International Workshop on Terminological Logic was the follow-up event to the "Workshop on Term Subsumption Languages" held in Jackson Village, New Hampshire, in October 1989 (cf. AI Magazine 11(2)).

Terminological Logics consists of a family of representation formalisms that grew out of the KL-ONE knowledge representation system. Unlike some other areas of knowledge representation, in this field the aspects of theoretical work (semantical foundations, complexity), system-oriented work (implementational issues), and application-oriented work are all dealt with within one community, as documented by the variety of talks at this workshop.

The workshop itself brought together 40 invited participants currently working in the field, and served to provide a snapshot of the current state of research, showing that there has been a lot of progress in the last several years. The theoretical area has advanced to a point where only a few questions concerning the core formalism remain open. The current trend seems to be to integrate more functionality and other formalisms.

In addition to the scheduled sessions, there were a number of informal meetings for exchanging ideas and planning future collaborative work, including one about future system standards and standard notation. This should make the exchange of ideas, systems, and knowledge bases, and the maintainance of a test corpus easier in the future.

The program was rounded off by an overview talk by Ron Brachman on the past and future development of Terminological Logics (the issue of finding a good name for the field is still in discussion), and a panel debate on aspects of the relationship between "Theory and Practice". In order to promote communication between people working in the field a mailing list ( was established.

We would like to thank the Dagstuhl foundation for inviting us, our affiliated organizations for their support, Kirstin Ost for compiling this report, and finally all participants for their active engagement in the workshop.


  • B. Nebel
  • C. Peltason
  • K. v. Luck