From: n@predict.COM@santafe.EDU (Norman Packard)
Subject: [rucker@sjsumcs.SJSU.EDU: evolving cas]
Reply-To: n%predict.com@santafe.edu
Organization: The Internet
Distribution: inet
Date: Wed, 6 Jan 1993 16:41:03 GMT

    Lyman,

    Thanks for the message.  Regarding evolution of CA's, two points:

    -- Rucker correctly indicates that I wrote an article on evolution
    of a population 1D CA's with a fitness function that rewarded
    classification of initial conditions on the basis of the density
    of nonzero sites.  Evolution was somewhat successful, though very
    time consuming (each computation of the fitness of each individual
    involved an average of many runs).

    Melanie Mitchell, now at the Santa Fe Institute (mm@santafe.edu),
    has recently been following up these experiments.  One of her most
    interesting results is that one of my conclusions might be wrong.
    In particular, the conclution quoted in the title of my paper,
    "evolution toward the edge of chaos".  Her experiments indicate
    that the peaking of the population near the edge of chaos that I
    observed is probably due to an artifact of the genetic algorithm I
    used (in particular, a diversity mechanism to throw evolution off
    local maxima).  She has a paper coming out soon.

    -- Regarding "Blind Watchmaker" style evolution, below I enclose a
    proposal for a project that never happened.  I envisioned it to
    take place somewhere like Disneyland.

    I am not sure that evolving CA's on the most microscopic level
    (entries in the rule table) would give enough access to aesthetic
    patterns to make the evolutionary game fun.  Having knobs (genetic
    operators) control other more global properties of the CA (eg.
    densities of particular symbols in the rule table) might be good,
    or moving to variation of continuous parameters in a lattice map
    (CA with continuous variables at each site) might be good.

    Obviously, the same idea could work with any class of pattern
    generating dynamics.  L-systems might be very good.

    	Yours,
    	Norman

_______________________________________________________________________________
\documentstyle[12pt]{article}
\begin{document}
\title{Evolving Art\\
A Proposal for an Exhibit}
\author{Norman H. Packard\\
via Montebello 30\\
20121 Milan Italy}
\date{April, 1989}
\maketitle

Recent research on evolving and adaptive systems suggests an idea for
a large scale exhibit, suitable for a museum or other public display. 
The exhibit would have the following appealing features: (i) it is 
interactive, (ii) it is visually appealing, (iii) as people interact
with it, the exhibit itself would constantly evolve, (iv) it would
constitute an ongoing research project on a scale impossible to
achieve any other way.\\
\ \\
The background for the idea comes from looking at adaptation in the
space of cellular automaton (CA) rules.  The essential idea of the
exhibit is to use people's sense of aesthetics as the fitness
function, and to use people interacting with the exhibit as food for
a genetic algorithm that would create an evolutionary tree of cellular
automata, which would become increasingly beautiful with time.

\section*{Presentation}
Roughly, my idea for the appearance of the exhibit would be to have
one very large color monitor that would be the centerpiece of the
exhibit and several other visually separate large color monitors 
(at least 12), showing the dynamics of the current population of 
two dimensional cellular automaton rules.  Each rule will be simulated
by special purpose hardware that presents a spectacular, constantly 
changing, complex two dimensional image on one of the monitors.

In front of the monitors would be terminals for people to use, more
than one, (a minimum of four should be sufficient) so that one person 
interacting with the exhibit could enhance others to try.  Each
terminal would have an interactive graphical interface, probably 
mouse driven with no keyboard, and also a color monitor to the side.  
The user would use the interface to choose members of the CA
population, and use them experimentally to create new genetic
varieties by mutation and crossover of them, seeing the results on the
color monitor to the side.

The large monitors would be divided into two rows.   Participants
would be able to put their entries into the population only on the 
bottom row, replacing an existing one of their choice.  The top row 
could be read by the participants, but not altered.  It would consist 
of the strongest rules in the population, where strength is measured 
by popularity... the more times a rule is selected for use, the
stronger it becomes.  Thus, if a rule on the bottom row is selected 
enough times, it may be moved up to the top row.  The strongest rule 
in the population at any given time, would be presented on the
largest, centerpiece color monitor.

All the exhibit computers would have to be networked together for them
to all participate in the same evolutionary experiment. The graphical
interface could display the evolutionary tree of present rules, and 
trace through a rule's evolution, possibly allowing the user access to
previously existing possibilities.  A color printer could be available
so that people could obtain a color output of their favorite rule 
(perhaps for a small fee to support the printer).

\section*{Equipment}
The best computation engine for this job is Toffoli's CAM.  The
advantages of the CAM are obvious, low price and very good performance
when it comes to iterating cellular automata.  The user interface
should be on another machine.  The software interface that comes with 
the CAM is much too sophisticated for museum use, and is not 
straightforwardly networked.  The essential features for the  user 
interface machine are (i) high resolution graphics (ii) software tools
for a mouse driven graphics interface  (iii) capability to be
networked together easily.  I have in mind some form of Unix workstation.

\section*{Development}
This would probably take six months to a year of  concerted effort for
two or three people.   It would be essential to have both good software 
and hardware people.

My rough estimate for the cost of both the development and the final
equipment is \$200,000.

\section*{Other Aspects}
(i)  Development costs might be split between more than one museum,
with more than one final exhibit.  The computers for each of the
exhibits could be linked together to form a single large evolving 
system.  (ii)  The same basic idea of an evolving exhibit would also 
be applicable to other classes of photogenic dynamical systems. One 
possibility is L-systems, for which several versions of display
software on personal computers are already available.

\section*{Scientific Goals:}
There are several fundamental questions that this exhibit might shed
light on:  (i)  What are the characteristics of co-adaptive evolution?
How fast does it take place?  Does evolution happen in a continuous 
fashion, or with occasional large changes in the population? Is there 
any direction in the evolution, i.e. evolution toward rules with
specific kinds of properties?   (ii) What is the nature of aesthetics?
Is there a well-defined "average" sense of aesthetics?  Does the 
collective aesthetic tend toward images with well defined visual 
properties, or classes of properties?

\section*{Images:}
Below are example images generated by two-dimensional cellular
automata.  Naturally these are snapshots, and can only give a crude
impression of what the dynamic images would look like.

\end{document}