Article View: comp.lang.misc
Article #4032Re: Will this *thread* ever halt?
From: David Gudeman
Date: Wed, 22 May 1991 04:53
Date: Wed, 22 May 1991 04:53
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In article <30835@dime.cs.umass.edu> victor yodaiken writes: ]In article <3410@optima.cs.arizona.edu> gudeman@cs.arizona.edu (David Gudeman) writes: ]>In article <30814@dime.cs.umass.edu> victor yodaiken writes: ]>]... I argue that it is possible, in theory, for a C ]>]compiler to detect all paths that lead to non-terminating loops and to ]>]flag these paths. ]>I argue that this is impossible in theory. ]Your argument is that the task is difficult... ].. Impractical != impossible. You must understand "in theory" in a ]nonstandard way. No, it's just that you seem to be trying to be trying to have it both ways: "Since a computer has a finite number of states, it is possible in principle to solve the halting problem for it, since you can always just traverse all possible states." The first part of the sentence implies that you are modeling a computer as an FSM. The second part of the sentence implies that you are modeling a computer as a non-finite state machine, since you are assuming that you can traverse all possible states. Pick your model. No matter which one you pick, you cannot solve the halting problem for all programs on a given machine with a program on that machine. -- David Gudeman gudeman@cs.arizona.edu noao!arizona!gudeman
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!elroy.jpl.nasa.gov!ncar!noao!arizona!gudeman From: gudeman@cs.arizona.edu (David Gudeman) Newsgroups: comp.lang.misc Subject: Re: Will this *thread* ever halt? Message-ID: <3430@optima.cs.arizona.edu> Date: 22 May 91 04:53:07 GMT Sender: news@cs.arizona.edu Lines: 27