Article View: sci.logic
Article #264Re: A only if B
From: DANIEL F COHEN
Date: Wed, 14 Oct 1992 23:09
Date: Wed, 14 Oct 1992 23:09
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In article <rkaivola.718902434@mits> rkaivola@mits.mdata.fi (Risto Kaivola) writes: > Exactly how should one formalize the English notion of 'only if' >in the language of the propositional calculus? > That is, given the sentence >"Tom will visit us only if we invite him.", >is the correct formalization >A = "Tom will visit us." >B = "We invite him." >A --> B Exactly. The only assignment of truth-values which makes 'A only if B' false is when A is true and B is false. Same truth value assignments as A->B. --Dan
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Newsgroups: sci.logic Path: arc1-ca.pugleaf.net!sparky!uunet!charon.amdahl.com!pacbell.com!iggy.GW.Vitalink.COM!cs.widener.edu!eff!news.byu.edu!news.mtholyoke.edu!nic.umass.edu!titan.ucc.umass.edu!danco From: danco@titan.ucc.umass.edu (DANIEL F COHEN) Subject: Re: A only if B Message-ID: <Bw4wCn.Jqy@nic.umass.edu> Sender: usenet@nic.umass.edu (USENET News System) Organization: University of Massachusetts, Amherst References: <rkaivola.718902434@mits> Date: Wed, 14 Oct 1992 23:09:58 GMT Lines: 50