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From: aboulang@BBN.COM (Albert Boulanger)
Newsgroups: comp.parallel
Subject: Re: "Asynchronous" way of thinking
Message-ID: <1991May27.121658.7300@hubcap.clemson.edu>
Date: 25 May 91 21:49:51 GMT
References: <1991May23.120018.17449@hubcap.clemson.edu>
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In-Reply-To: androula@ecn.purdue.edu's message of 21 May 91 17:31:58 GMT


In article <1991May23.120018.17449@hubcap.clemson.edu> androula@ecn.purdue.edu (Ioannis Androulakis) writes:


   My main interest is the implementation of iterative algorithms
   in an asynchronous computing environment. There is no doubt
   that asynchronicity has many advantages as well as disadvantages.
   But, from my point of view, there exists a much more interesting
   question that needs to, at least, be explored.
   Is it possible to make use of the concept of asynchronicity
   and develop a NEW WAY OF THINKING,
   a new way of approaching the problems,
   that will lead us to completely
   new algorithms that will make full use of the power of the
   asynchronous mode of operation and that would not be simple
   asynchronous implementations of the existing sequential 
   algorithms?


I agree. My interest in asynchronous algorithms was sparked by how
much like quantum mechanical systems they are. Conjugate variables in
QM maps to variables being iterated across processors. In fact I did
a orbiting electron simulation with classical dynamics so that the
momentum variables were being updated on one processor and the
position variables on another, asynchronous to each other. This was a
way of making use of the observer/observed interaction effect
well-known to multiprocessing folk and link it to the something real in
the system being simulated.  Asynchronous systems are open systems and
the results of computation are partially influenced by the external
coupling environment. This leads to a kind of high-dimensional noise
(you can read this as nondeterminism if you like) available for
"free". This is all very similar to "non-local" hidden variable
theories in QM. Asynchronous behavior of neural nets is a ripe are of
investigation. 

Anyway, a good reference to asynchronous iterative algorithms is the book:

"Parallel & Distributed Computation: Numerical Methods"
Dimitri Bertsekas, & John Tsitsiklis


Seeking space-time pictures of an asynchronous universe,
Albert Boulanger
aboulanger@bbn.com