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GECCO Discussion on Coevolution Task Force
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R. Paul Wiegand  
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 More options Jul 25 2007, 9:28 pm
From: "R. Paul Wiegand" <p...@tesseract.org>
Date: Wed, 25 Jul 2007 04:28:52 -0700
Local: Wed, Jul 25 2007 9:28 pm
Subject: GECCO Discussion on Coevolution Task Force
GECCO REPORT

As readers of this forum know, I attempted to collect a group of
people to discuss some of the issues raised in a recent thread on this
website about the Coevolution Task Force itself.  This attempt was
only marginally successful:  Despite the post here and on the GECCO
wiki, interest in such a discussion was modest.

Nevertheless, a few of us did sit down to talk about the TF.  Our
conversation touched on three main questions ... some of which we
answered there, some of which I've pieced together after subsequent
email exchanges.

  1. What is the "Computational Intelligence and Coevolution Task
Force"?
  2. How do "we" and our activities relate to it?
  3. On a broader level, what might be some of the goals of the
coeovlution community?

I'll take them in turn

1. COEVOLUTION TASK FORCE

For those that do not know (I didn't):  The IEEE has what they call
the "Computational Intelligence Society" ( http://ieee-cis.org/ec/ ),
which has the goal of promoting research, development, and teaching of
such techniques.  It is composed of a number of "Technical
Committees", subgroups with more focused fields of study ...
evolutionary computation is one.  As far as I can see the ECTC is
analogous to ACM SIGEVO ... it has a governing board, by-laws, helps
organize conference and other events, etc.

Those who have interests in a subfield of study that they believe
would benefit from an even more focused group may propose such to the
ECTC.  Indeed, the "Coevolution working group" was established by
Graham Kendall a couple of years ago.  It took the form of a largely
inactive mailing list.  I don't know if anything else came of it.

Recently this group was converted to a "Task Force", and we moved to a
Google group, rather than a simple mail list.  Phi has already covered
what this means in previous posts.  The inference I have taken is that
the advantage to being a part of such a group is to consolidate
discussion and possibly receive some resources from IEEE to sponsor
some events, etc.  In exchange, the TF has to demonstrate to IEEE that
it is a productive use of such resources.

As far as I can tell the "Computational Intelligence" prefix to the
group's name is merely a hierarchical artifact:  The Coevolution task
force is a part (ultimately) of the Computational Intelligence
Society ... the task force is dedicated to the field of coevolutionary
computation.

2. HOW "WE" RELATE

The group of people with whom I most commonly collaborate for
activities and events related to coevolution have historically
operated in a very informal, self-organizing fashion.  We neither
consider ourselves operating "officially" as an extension of the ACM
nor of IEEE.  We're just a group of people who share an interest and
expertise in coevolutionary computation.

Nevertheless, it was clear and not surprising that most of us involved
in the GECCO discussion have participated more in the ACM events than
the IEEE events.  The relevance here was that we were all fairly
unknowledgeable about what the task force had done in IEEE contexts.

As an informal group, we've accomplished quite a bit (an example list
appears elsewhere in a contemporary post).  And part of our discussion
centered around what we would be gaining and losing if we shifted our
activities to be under one umbrella or another.  Would there be a loss
of autonomy?  What kind of resources would be available to us?  Etc.

We concluded that we'd like to know more about what the IEEE folks are
up to in the coevolution community, and we'd like for them to know
more about what we are doing.  In that sense, a periodic discussion on
this web resource might be quite useful.  Moreover, if the TF can
facilitate something for our community in a way that we, ourselves,
could not, then that might be worth exploring.  However, I do not have
the sense that we had any specific ideas on this front over and above
what we are already accomplishing in our informal setup.

I think this point was left very much unresolved.

3. BROADER GOALS

We all agreed that the coevolutionary computation community has made a
lot of great progress over the last few years, but also admitted there
were some things bothering us.  There is the concern that the same
people are publishing at about the same rate:  We aren't growing.
There's also the perception that contemporary views of coevolution
that include a clearer formal foundation are not being considered in
applied studies as much as we'd like, and that coevolution really
isn't raising in scope within the general EC community.

How we might use IEEE resources to accomplish these goals is unclear
to us.  More generally we'd no specific ideas on how to remedy these
issues ... we are already holding workshops, tutorials, discussion
forums, etc.  The high-level question here is:  Is it better to
address these issues top-down (IEEE Task Force) or bottom-up
(informal, ad-hoc organizations?

The more specific question is what could be done about it, regardless?

One idea is to target students a bit more carefully.  We might hold a
separate workshop-like event for students where we try to provide as
much funding for them to attend as possible, provide a strong set of
background lectures in foundational elements of coevolution, have
competition on realistic problems, and maybe even have a few broader
discussions that graduate students might find useful (funding,
publishing, job hunting, etc.).

We might also try to develop a competition in one or both of the major
conferences.  I know GECCO has a mechanism for such things.

Another idea is to push harder for strong example applications where
the advantage of a properly constructed coevolutionary algorithms were
clear, etc.


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phi  
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 More options Jul 25 2007, 9:56 pm
From: phi <PhilipHings...@gmail.com>
Date: Wed, 25 Jul 2007 11:56:20 -0000
Local: Wed, Jul 25 2007 9:56 pm
Subject: Re: GECCO Discussion on Coevolution Task Force
Hi Paul, everyone

Thanks Paul for this very thoughtful and useful report, and for
organising the meeting at GECCO.

I volunteer to organise a similar meeting at CEC. Perhaps those
interested could reply to me.

One concrete suggestion to make the foundations of coevolutionary
algorithms more widely considered (in particular,
better known to IEEE people, if there is such a concept!) might be a
special issue of IEEE TEC on coevolution. Any
volunteers for guest editors?

I've noticed quite a few papers published in TEC or in IEEE
conferences that use coevolution. Games is one area where
coevolution seems to be a natural approach. Another active area
recently is various new coevolution-based multi-objective
optimisation algorithms. I would personally like to see this work take
more account of proper foundations.

The competitions idea is also a good one. CEC does indeed have a
competitions program. In fact, I am responsible for
EC competitions at next year's WCCI in Hong Kong, and would welcome a
coevolution-based competition proposal.
The call for proposals may be found on the conference home page at
http://www.wcci2008.org/index.htm.

cheers

On Jul 25, 7:28 pm, "R. Paul Wiegand" <p...@tesseract.org> wrote:


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Anthony Bucci  
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 More options Jul 26 2007, 7:31 am
From: "Anthony Bucci" <abu...@gmail.com>
Date: Wed, 25 Jul 2007 17:31:17 -0400
Local: Thurs, Jul 26 2007 7:31 am
Subject: Re: [coevolve] Re: GECCO Discussion on Coevolution Task Force

I agree with Philip's comment on the need for coevolutionary approaches to
multi-objective algorithms to take better account of new theory.  My own
work has drawn strong ties between coevolution and multi-objective
optimization.  More broadly, Pareto coevolution can be seen as a set of
concepts and class of algorithms which make the connection explicit.  There
has been quite a bit of work on this topic recently, including my own
dissertation as well as a recent book chapter I co-authored with Edwin de
Jong for a new book on Multi-objective Problem Solving from Nature.  Of
course I have a vested interest in seeing the connections between coev and
MOO made as strong as possible  Still, I think any approach to coev could
benefit by taking account of recent theoretical advances.

Regarding a competition, I think tic-tac-toe is a good challenge problem
because:

(a) it's a small game with simple, known minimax strategy, giving a
benchmark for progress

(b) it has a small, easily enumerable set of board configurations, allow
strategies to be written out explicitly and examined critically

(c) there's a nice history of work on tic-tac-toe, starting with Michie's
MENACE, through Susan Epstein's Hoyle system, to more recent work in coev

(d) it's proven to be particularly challenging for coevolutionary algorithms
for some as-yet-obscure reason.  some attempts, like Pete Angeline's, never
resulted in optimal strategies (though he made the problem harder than it
needed to be, as he was exploring other questions than finding optima).
others, like Rosin's, required specially-designed representations and a huge
number of evaluations before optimal solutions were found.

Even modern coevolutionary algorithms like Sevan's Nash memory tend to have
trouble with tic-tac-toe.  I have some thoughts on why this is, but it's
very much an open question how we could get coevolution to efficiently find
optimal tic-tac-toe strategies.  A metric of success would be the ability to
evolve optimal players using fewer evaluations than Rosin did and a weaker
representation -- that'd be a publishable result, it seems to me.

The CA majority problem isn't a bad choice either, as there is also a good
history of work on it (including Sevan's).  I personally prefer tic-tac-toe,
though.

Anthony

On 7/25/07, phi <PhilipHings...@gmail.com> wrote:


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Kenneth Stanley  
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 More options Jul 27 2007, 11:54 am
From: Kenneth Stanley <kstan...@cs.ucf.edu>
Date: Thu, 26 Jul 2007 18:54:49 -0700
Local: Fri, Jul 27 2007 11:54 am
Subject: Re: GECCO Discussion on Coevolution Task Force
I also think tic-tac-toe is currently an important domain because it
*should* be easy but isn't.  However, I think it would be most
informative to separate the genetic encoding from the coevolutionary
algorithm because in tic tac toe the genetic encoding can be a
significant factor in success.

Therefore, what I think would be useful is to agree on a single
encoding.  It is actually possible with today's processors to find a
perfect player without coevolution through an exhaustive evaluation
that tests all possible game positions (minus ones that are simply
continuations of completed games).  That is, an optimal strategy can
be evolved using such a non-coevolutionary exhaustive evaluation as a
proof of concept that the encoding can indeed solve tic-tac-toe
perfectly.

One we know that, it becomes interesting to pit different
coevolutionary techniques against each other with that same encoding
in each case.  Then we would know the coevolutionary methodology is
the only determining factor in differing performance.

ken

On Jul 25, 5:31 pm, "Anthony Bucci" <abu...@gmail.com> wrote:

...

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phi  
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 More options Aug 2 2007, 7:04 pm
From: phi <PhilipHings...@gmail.com>
Date: Thu, 02 Aug 2007 09:04:29 -0000
Local: Thurs, Aug 2 2007 7:04 pm
Subject: Re: GECCO Discussion on Coevolution Task Force
OK - time to show my ignorance... I've quickly had a look at a few
papers, but I guess I don't get it!
How can tic-tac-toe be any challenge? The game tree is tiny. Not much
opportunity for something hard like,
say, opponent modelling.

Is it something about co-evolution that makes it hard? Would it be
hard for standard evolution (or whatever the right name
for not co-evolution, but still evolution is). I realise you'd need a
fitness measure: say performance against perfect play, or
maybe against a random player.

phi

On Jul 27, 9:54 am, Kenneth Stanley <kstan...@cs.ucf.edu> wrote:

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Anthony Bucci  
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 More options Aug 3 2007, 5:49 am
From: "Anthony Bucci" <abu...@gmail.com>
Date: Thu, 2 Aug 2007 15:49:24 -0400
Local: Fri, Aug 3 2007 5:49 am
Subject: Re: [coevolve] Re: GECCO Discussion on Coevolution Task Force

If you think tictactoe is easy, then I'd say show me some results.
Replicate Rosin and see if you can do better.  :-)

Or:

Don Michie showed training MENACE against minimax did not produce very good
players; he did that work in the 60's?  70's?  Susan Epstein's 1994 ideal
trainer article in Machine Learning argues the case more fully, for more
games.  She also argues against using random legal move generators for
training.  Though the game tree is small, training against either minimax or
a random player still sends you into bizarre paths of the tree and does not
sample the configs you're likely to see in practice.  Random legal move
generators also don't have coordinated strategy across moves.  There's
danger of forking in tictactoe.  A good player will try to set up forks, but
doing so requires coordinating at least two moves.  A random legal move
generator is unlikely to do that consistently.  So a player trained against
a random player is unlikely to have learned how to protect against forks
(you can try all this yourself and see how tricky it is pretty easily).

Michie trained MENACE by playing good moves (e.g., those selected by
minimax) frequently, but then purposely choosing poor moves once in awhile.
As far as I remember he didn't have a system for choosing "poor" moves; I
think he used his own intuition and knowledge about what parts of the game
tree had already been explored.

A common observation when coevolving tictactoe players is that the
population rapidly converges onto players which draw one another.  Finding
players that win seems to be hard.  If you pressure the players to win, then
you have almost no gradient (because players found early in the run cannot
win very much).  If you pressure players to draw, then you get stuck with a
bunch of players who draw but don't win.  Various weightings of those two
objectives don't seem to help the getting stuck bit.

Naturally, using a good representation helps with those issues.  Tictactoe
is small enough that you can learn the evaluation function as a table.  But
that's cheating, because you can't do that for bigger games (without taking
account of symmetries and without excluding terminal boards, tictactoe still
only has ~5,500 configurations.  What does checkers have, 10^40?  You can't
store a lookup table, and you have a paucity of stimulus problem with RL).
If you try to learn a neural network representation of the evaluation
function instead, as you'd have to do with bigger games, then you run into
problems.

Check out Pete Angeline's 1993 paper on evolving/coevolving tictactoe
players (he argues that coevolved players are less brittle than those
evolved against fixed opponents).  Chris Rosin's 1997 PhD dissertation
reports experiments on tictactoe, also (and even with a "nice"
representation, coevolving an optimal player requires billions of games to
be played).

Anthony

On 8/2/07, phi <PhilipHings...@gmail.com> wrote:

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Philip Hingston  
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 More options Aug 3 2007, 7:14 pm
From: "Philip Hingston" <philiphings...@gmail.com>
Date: Fri, 3 Aug 2007 17:14:03 +0800
Local: Fri, Aug 3 2007 7:14 pm
Subject: Re: [coevolve] Re: GECCO Discussion on Coevolution Task Force

OK. I'm surprised. Or maybe shocked! I'll have to put that on my list of
things to try. Thanks.

Anyway, in that case, maybe this would be a good idea for a competition. The
rules would need some care.

On 8/3/07, Anthony Bucci <abu...@gmail.com> wrote:

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