Article View: sci.logic
Article #309Re: Impredicativity - was: Russell's Paradox
From: Randall Holmes
Date: Fri, 06 Nov 1992 19:18
Date: Fri, 06 Nov 1992 19:18
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In article <1992Nov5.174527.22908@CSD-NewsHost.Stanford.EDU> pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt) writes: >In article <1992Nov5.164251.29649@guinness.idbsu.edu> holmes@garnet.idbsu.edu (Randall Holmes) writes: >>You do not "weaken" FA to AFA; ZFC- + FA and ZFC- + AFA are both >>stronger than ZFC-, but neither is stronger than the other. > >I guess this must be another of my misconceptions. My general >impresssion was that AFA was automatically true under FA, by virtue of >the latter saying that only "unwound" graphs were permitted, and that >every chain on the unwinding had to terminate. So what's an example FA >situation contradicting AFA? >-- >Vaughan Pratt There's no truth in logic, son. AFA asserts the existence of a set (only one) which is its own sole element; FA asserts the impossibility of such a set. -- The opinions expressed | --Sincerely, above are not the "official" | M. Randall Holmes opinions of any person | Math. Dept., Boise State Univ. or institution. | holmes@opal.idbsu.edu
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Newsgroups: sci.logic Path: arc1-ca.pugleaf.net!sparky!uunet!pmafire!mica.inel.gov!guinness!garnet.idbsu.edu!holmes From: holmes@garnet.idbsu.edu (Randall Holmes) Subject: Re: Impredicativity - was: Russell's Paradox Message-ID: <1992Nov6.191800.17025@guinness.idbsu.edu> Sender: usenet@guinness.idbsu.edu (Usenet News mail) Nntp-Posting-Host: garnet Organization: Boise State University References: <1992Nov4.073717.22625@CSD-NewsHost.Stanford.EDU> <1992Nov5.164251.29649@guinness.idbsu.edu> <1992Nov5.174527.22908@CSD-NewsHost.Stanford.EDU> Date: Fri, 6 Nov 1992 19:18:00 GMT Lines: 21