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Predicate Modal Logics Do Not Mix Very Well

✍ Scribed by Olivier Gasquet


Publisher
John Wiley and Sons
Year
1998
Tongue
English
Weight
246 KB
Volume
44
Category
Article
ISSN
0044-3050

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✦ Synopsis


Abstract

The problem of completeness for predicate modal logics is still under investigation, although some results have been obtained in the last few years (cf. [2, 3, 4, 7]). As far as we know, the case of multimodal logics has not been addressed at all. In this paper, we study the combination of modal logics in terms of combining their semantics. We demonstrate by a simple example that in this sense predicate modal logics are not so easily manipulated as propositional ones: mixing two Kripke‐complete predicate modal logics (one with the Barcan formula, and the other without) results in a Kripke‐incomplete system.