Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!quintus!ok
From: ok@quintus.uucp (Richard A. O'Keefe)
Newsgroups: comp.ai
Subject: Re: Capabilities of "logic machines"
Message-ID: <696@quintus.UUCP>
Date: 18 Nov 88 02:22:18 GMT
References: <8673@bcsaic.UUCP>
Sender: news@quintus.UUCP
Reply-To: ok@quintus.UUCP (Richard A. O'Keefe)
Organization: Quintus Computer Systems, Inc.
Lines: 40

In article <8673@bcsaic.UUCP> ray@bcsaic.UUCP (Ray Allis) writes:
>Whoa!  Wrong!  (Well, sort of.)  I think you conceded much too quickly.
>'Simulate' and 'model' are trick words here.

Correct.  A better would would be _emulate_.
For any given electronic realisation of a neural net,
there is a digital emulation of that net which cannot be
behaviourally distinguished from the net.
The net is indeed an analogue device, but such devices are
subject to the effects of thermal noise, and provided the
digital emulation carries enough digits to get the
differences down below the noise level, you're set.

In order for a digital system to emulate a neural net adequately,
it is not necessary to model the entire physical universe, as Ray
Allis seems to suggest.  It only has to emulate the net.

>You see, all the ai work being done on digital computers is modelling using
>formal logic.

Depending on what you mean by "formal logic", this is either false or
vacuous.  All the work on neural nets uses formal logic too (whether the
_nets_ do is another matter).

>>much like a logical machine -- pushing symbols around, performing
>>elementary operations on them one at a time, until the input vector
>>becomes the output vector. I have trouble imagining that is what is
>>going on when I recognize a friend's face, predict a driver's
>>unsignaled turn by the sound of his motor, realize that a particular
>>computer command applies to a novel problem, etc.

>Me, too!

Where does this "one at a time" come from?  Most computers these days
do at least three things at a time, and the Connection Machine, for all
that it pushes bits around, does thousands and thousands of things at
a time.  Heck, most machines have some sort of cache which does
thousands of lookups at once.  Once and for all, free yourself of the
idea that "logical machines" must do "elementary operations one at a
time".