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From: stephen@pesto.uchicago.edu (Stephen P Spackman)
Newsgroups: comp.lang.misc
Subject: Re: Halting Problem Solved! Film at 11! (Was Re: definitions)
Message-ID: <STEPHEN.91May7205714@pesto.uchicago.edu>
Date: 8 May 91 02:57:14 GMT
References: <2861@optima.cs.arizona.edu>
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Organization: University of Chicago CILS
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In-Reply-To: gudeman@cs.arizona.edu's message of 7 May 91 19: 16:05 GMT

In article <2861@optima.cs.arizona.edu> gudeman@cs.arizona.edu (David Gudeman) writes:

|If you want to get theoretical, then you can _theoretically_ keep
|buying tapes until the world's supply of tape runs out.  Then you can
|manufacture more.  When you use up all the earth's supply of materials
|for making tapes, you can build mining space ships.  The question of
|whether a computer is a finite-state device or not boils down to the
|question of whether the universe holds a finite amount of material for
|making tape.  In this case whether you believe that a computer is a
|finite-state device depends on whether you believe there is a finite
|amount of matter in the universe.

There is definitely and without question a finite amount of matter in
the universe that I am willing to make tapes out of.

For more than a finite amount of matter to become available to us on a
timescale in which we are in an energetic position to make some use of
it, would require certain (IMHO unlikely) breakthroughs in physics.

|The question of whether an electronic computer is an FSA or an
|infinite-state device is not as trivial as most people seem to think.

Evidently, I disagree. I am PERSONALLY willing to engineer my
compilers on the assumption that (a) FTL travel, (b) many-worlds
parallelism and (c) anything comparably revolutionary will not become
available within the useful lifetime of the software.

And even WITH those breakthroughs, I still think computers would for
the most part remain finite, making finite computation a useful field
of research.
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stephen p spackman         Center for Information and Language Studies
systems analyst                                  University of Chicago
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