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From: CLT@SU-AI.ARPA
Newsgroups: net.ai
Subject: Incompleteness in Modal Logic
Message-ID: <17415@sri-arpa.UUCP>
Date: Fri, 9-Mar-84 04:34:00 EST
Article-I.D.: sri-arpa.17415
Posted: Fri Mar  9 04:34:00 1984
Date-Received: Tue, 13-Mar-84 07:56:49 EST
Lines: 29

From:  Carolyn Talcott 

           [Forwarded from the CSLI bboard by Laws@SRI-AI.]

Subject: SEMINAR IN LOGIC AND FOUNDATIONS OF MATHEMATICS
SPEAKER: Johan van Benthem, University of Groningen

TITLE:  "From Completeness Results to Incompleteness
         Results in Modal Logic"

TIME:   Wednesday, Mar. 14, 4:15-5:30 PM
PLACE:  Stanford Mathematics Dept. Room  383-N


  For a long time the main activity in intensional logic
consisted in proving completeness theorems, matching some
logic with some modal class.  In the early seventies,
however, various incompleteness phenomena were discovered -
e.g. such a match is not always possible.  By now, we know that
the latter phenomenon is the rule rather than the exception,
and the issue of the `semantic power' of the possible worlds
approach has become a rather complex and intriguing one.

  In this talk I will give a survey of the main trends in the
above area, concluding with some open questions and partial
answers.  In particular, a new type of incompleteness theorem
will be presented, showing that a certain tense logic defies
semantic modelling even when both modal class and truth
definition are allowed to vary.