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From: khorsell@ee.latrobe.edu.au (Kym Horsell)
Subject: Re: Reversing Life/C.A.s
Sender: news@lugb.latrobe.edu.au (News System)
Message-ID: <3qgqf2$3k3@fourier.ee.latrobe.edu.au>
Date: Wed, 31 May 1995 04:14:26 GMT
Lines: 17
References: <3qfrnv$q4h@ns.cityscape.co.uk>
Organization: Department of Electronic Engineering, La Trobe University

In article <3qfrnv$q4h@ns.cityscape.co.uk>,
Kasprzyk  <dr37@cityscape.co.uk> wrote:
>I remember hearing that someone had been able to reverse the "Game of Life". ie. run it 
>for a while, then hit a button and watch it go back to what it started as.
>
>How did they do this?
>
>Can this be generalised for any C.A. (even 3-D ones )?

I believe there is a theorem to the effect that if a CA is reversible then
it is not interesting. Conway's life is not reversible -- the mapping
from t to t+1 is a function but NOT vice-versa (i.e. there may be more than 
one predecessor state for a given state).

-- 
R. Kym Horsell
khorsell@EE.Latrobe.EDU.AU              kym@CS.Binghamton.EDU 
