Re: 'not an artist' article

[Steve Baker <sjbaker1@airmail.net>]

Erik wrote:

> Here I thought I was a supergenious having
> this idea, and it turns out everyone and their brother is thinking along the
> same lines.

Genetic algorithms are becoming pretty commonplace these days.
 
> One problem with evolving systems in software is that it uses a lot of
> technique that are primarily in the field of AI, and most programmers don't
> have a strong AI background.

For what I propose (evolving artwork) this isn't an issue.

The original biomorphs program was very simple - no AI at all.

The goal of the evolution is to please humans - hence a human has to say
which mutant lives and which dies on the basis of which one comes closest
to their idea of 'cute' or 'agressive' or whatever criteria is needed.

To misquote Darwin: It's a matter of "Survival of the Cutest".

People who have tried to use automatic selection criteria have
discovered that the critters that are produced have a tendancy
to exploit 'holes' in your criteria of bugs in the program.

I forget the name of the guy - but there was a SigGraph paper
a few years ago about this software package that evolved locomotion
systems - with the hope that it would create critters that could
walk, slither, crawl, whatever.

He set his selection criteria to be 'the creature that moved
furthest in a given (fixed) amount of time.

He ran the genetics for a gazillion generations - then viewed
the resulting population - expecting to see elegant running
machines or something.

What actually happened was that his critters evolved into
EXTREMELY tall, unstable structures that simply fell over.
Since his 'distance travelled' criterion measured the distance
travelled by the center of gravity of the critter, all they
had to do was to fall over in order to beat out any other
locomotion mechanisms.

The critters did what they were told - they produced an
extremely simple, elegant (and unexpected) solution to
the problem of moving the largest distance in 10 seconds.

He fixed that problem and found that critters would evolve
to do things like exploit a roundoff error in his friction
math to pick up energy from 'nowhere'.  Any bug or loophole
in the simulated 'world' would result in creatures evolving
to exploit it.

This is a hard-won lesson.

Your economic model had better be pretty tightly coded or
you'll end up with entire civilisations that evolve to
exploit pennies that end up lodged down the sides of
sofas.  :-)

-- 
Steve Baker   HomeEmail: <sjbaker1@airmail.net>
              WorkEmail: <sjbaker@link.com>
              HomePage : http://web2.airmail.net/sjbaker1
              Projects : http://plib.sourceforge.net
                         http://tuxaqfh.sourceforge.net
                         http://tuxkart.sourceforge.net
                         http://prettypoly.sourceforge.net

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