From newshub.ccs.yorku.ca!torn!cs.utexas.edu!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!destroyer!uunet!trwacs!erwin Mon Aug 24 15:41:02 EDT 1992
Article 6637 of comp.ai.philosophy:
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>From: erwin@trwacs.fp.trw.com (Harry Erwin)
Newsgroups: comp.ai.philosophy
Subject: Re: Freewill, chaos and digital systems
Message-ID: <702@trwacs.fp.trw.com>
Date: 18 Aug 92 16:34:58 GMT
References: <Bt4xt1.MA0.1@cs.cmu.edu>
Organization: TRW Systems Division, Fairfax VA
Lines: 41

rudis+@cs.cmu.edu (Rujith S DeSilva) writes:

>(1) Does freewill arise solely through the mechanism of chaos?

All the answers you'll get on this one will be speculative. I suspect
chaos is part of it, but not all.

>(2) Can digital systems exhibit chaos (as opposed to simulating it to a
>    limited extent)?

Theoretically no, since a finite state machine will be periodic,
eventually. The same answer, btw, holds for quantum mechanical systems.
Huberman and Hogg showed that. Realistically, though, the terminal
sequence for a finite state machine has a length about equal to the square
root of the total number of possible states. 2 to the 16th possible states
is large enough to effectively simulate chaos. Jim Yorke has done work in
this area. I've seen more recent stuff in the IEEE transactions. 

>(3) What if a digital system is coupled to a chaotic system, e.g., some sort
>    of unstable oscillator that can be sampled to give one bit of information?

That's kind of fun. Bernardo Huberman did some work with a couple of
Brazilian colleagues where he showed that you could get chaos in a quantum
system if you coupled it with something continuous, like a temperature
bath. Don Davis (Project Athena, MIT) has also done some work in this
direction. Tom Bell and I demonstrated chaos in real (as opposed to toy)
computer systems back in 1987. (Have you ever tried to get sign off on a
system where the acceptance tests were demonstrably not repeatable?)

>Just some random thoughts that popped into my head ... comments solicited.

>Rujith de Silva.
>Carnegie-Mellon University.

>// Ivy: What Roman golfers shouted //

Cheers,
-- 
Harry Erwin
Internet: erwin@trwacs.fp.trw.com



