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Article #300Re: Impredicativity - was: Russell's Paradox
From: Torkel Franzen
Date: Thu, 05 Nov 1992 20:05
Date: Thu, 05 Nov 1992 20:05
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In article <1992Nov5.170354.29866@guinness.idbsu.edu> holmes@garnet.idbsu.edu
(Randall Holmes) writes:
>Neither A nor B can be shown to represent a unique object in ZFC-.
Of course not! The question I was commenting on was whether it
is provable in ZF without foundation that if there is a function f
defined on the natural numbers satisfying f(n)={n,f(n+1)}, then there
is a set x such that x={1,x}, and my answer was that in all likelihood
this is not so.
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<Bx81Ho.9HL@cantua.canterbury.ac.nz> <TORKEL.92Nov5103134@isis.sics.se> <1992Nov5.170354.29866@guinness.idbsu.edu>Show Full Headers
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Path: arc1-ca.pugleaf.net!sparky!uunet!sun-barr!news2me.EBay.Sun.COM!cronkite.Central.Sun.COM!texsun!exucom.exu.ericsson.se!ericom!sunic!sics.se!torkel From: torkel@sics.se (Torkel Franzen) Newsgroups: sci.logic Subject: Re: Impredicativity - was: Russell's Paradox Message-ID: <TORKEL.92Nov5210509@lludd.sics.se> Date: 5 Nov 92 20:05:09 GMT References: <Bx81Ho.9HL@cantua.canterbury.ac.nz> <TORKEL.92Nov5103134@isis.sics.se> <1992Nov5.170354.29866@guinness.idbsu.edu> Sender: news@sics.se Organization: Swedish Institute of Computer Science, Kista Lines: 10 In-Reply-To: holmes@garnet.idbsu.edu's message of 5 Nov 92 17:03:54 GMT