Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!brutus.cs.uiuc.edu!apple!oliveb!amdahl!pacbell!osc!jgk
From: jgk@osc.COM (Joe Keane)
Newsgroups: comp.ai
Subject: Re: Reasons why you don't prove your programs are correct
Summary: Parallel processing is much different, but still Turing compatible.
Keywords: parallel processing
Message-ID: <1861@osc.COM>
Date: 14 Jan 90 22:34:44 GMT
References: <25711@cup.portal.com> <1449@krafla.rhi.hi.is> <1990Jan11.015531.20996@world.std.com> <9220@medusa.cs.purdue.edu> <1862@mrsvr.UUCP>
Reply-To: jgk@osc.COM (Joe Keane)
Organization: Object Sciences Corp., Menlo Park, CA
Lines: 14

In article <1862@mrsvr.UUCP> hallett@gemed.ge.com (Jeffrey A. Hallett (414)
548-5163) writes:
>Similarly, parallel-processing is just a bunch of sequential steps happening
>together.

You want something that can't be simulated on a Turing machine.  You're right
that adding parallelism doesn't change anything, although i don't know what
would.  Suppose you have a massively parallel optical computer that can
compute very complex functions in very small space, and can do computations at
different frequencies in the same space, and is also very big to boot.  Even
this could be simulated by a Turing machine, it's true.  But i don't think
it's a useful way to think about it.  It hides a lot of the important
properties of the computer.  So, what is a good way to think about it?  Hard
to say, since i've never used such a thing.