Article View: comp.lang.misc
Article #3797Re: The Halting Problem is _not_ solvable on real com
From: Darren New
Date: Thu, 09 May 1991 18:53
Date: Thu, 09 May 1991 18:53
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1646 bytes
In article <1991May9.122526.13533@s1.msi.umn.edu> dbae@s1.msi.umn.edu (David Epstein) writes: >>Proof: Suppose that Halt exists. Then define >> Paradox = (Halt::E(Paradox)) -> CLoop ; CAccept >>what is the result of running Paradox? > >Is this a misprint, David? You can't define Paradox in terms of >itself. If it is a misprint, can you please repost, as I would like to >study this. Paradox is not really defined in terms of itself in a recursive-call sense. E(Paradox) is the "source code" for the program Paradox. If you know how Halt, CLoop, and CAccept are written, then you know how Paradox is written (see the >> lines :-). Feed the Paradox program to Halt, and if Halt says it halts then loop, otherwise halt. Paradox never explicity calls itself (altho Halt might "call" Paradox in some way, in which case Halt doesn't halt and thus gives a "wrong" answer). -- --- Darren New --- Grad Student --- CIS --- Univ. of Delaware --- ----- Network Protocols, Graphics, Programming Languages, FDTs ----- +=+ Nails work better than screws, when both are driven with hammers +=+
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!sdd.hp.com!wuarchive!udel!ee.udel.edu From: new@ee.udel.edu (Darren New) Newsgroups: comp.lang.misc Subject: Re: The Halting Problem is _not_ solvable on real com Message-ID: <53143@nigel.ee.udel.edu> Date: 9 May 91 18:53:14 GMT References: <2990@optima.cs.arizona.edu> <1991May9.122526.13533@s1.msi.umn.edu> Sender: usenet@ee.udel.edu Organization: University of Delaware Lines: 21 Nntp-Posting-Host: estelle.ee.udel.edu