Article View: sci.logic
Article #104Re: Set theory and modal logic
From: logic
Date: Wed, 08 Apr 1992 16:01
Date: Wed, 08 Apr 1992 16:01
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943 bytes
In article <1992Apr7.124948.5325@vax.oxford.ac.uk>, loader@vax.oxford.ac.uk (R Loader) writes: > S4 and S5 (and most other common modal logics), are subsystems of classical > (non-modal) logic extended with the axiom: A iff \box A. Other stuff deleted.... > Ralph Loader, > Mathematical Institute, Oxford. S4 and S5 are supersystems, not subsystems, of classical logic.. Neither contain the axiom "A iff \box A", both contain the axiom "if \box A then A". Al Hart
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Path: arc1-ca.pugleaf.net!sparky!uunet!spool.mu.edu!umn.edu!noc.MR.NET!gacvx2.gac.edu!logic From: logic@gacvx2.gac.edu Newsgroups: sci.logic Subject: Re: Set theory and modal logic Message-ID: <1992Apr8.100146.689@gacvx2.gac.edu> Date: 8 Apr 92 16:01:45 GMT Article-I.D.: gacvx2.1992Apr8.100146.689 References: <1992Apr5.213320.27618@morrow.stanford.edu> <1992Apr7.124948.5325@vax.oxford.ac.uk> Organization: Gustavus Adolphus College, St. Peter, Minnesota Lines: 14