Computer Chess Club Archives




Subject: Hello from Edmonton (and on Temporal Differences)

Author: James Swafford

Date: 19:43:36 07/30/02

Hey everyone.  I'm at an AAAI conference in Edmonton.  It's ironic (to me)
that it's been mentioned here recently that Edmonton is a hive of computer
chess enthusiasts.  I don't know if that's true (what's a "hive"? :-), but
there are certainly a few...

Now to my question.  I asked Jonathon Schaeffer today (who is a really
nice guy, IMO) some questions about his experience with TD learning
algorithms.  He's (co?)published a paper entitled (something like)
"Temporal Difference Learning in High Performance Game Playing."  I
thought the title was a bit misleading, because he focused on checkers.
Checkers programs have much smaller evaluation fuctions than chess
programs, obviously.  I asked him if he thought the TDLeaf(Lambda)
algorithm had potential in high calibre chess.  (Yes, yes, I know
all about Knightcap... but that wasn't quite "high" calibre.)
He responded with a very enthusiastic "yes".  He said "I'll never manually
tune another evaluation function again."

A natural follow up question (which I also asked) is -- then why isn't
everyone doing it??  I don't _believe_ (and maybe I'm wrong about this)
that any top ranked chess programs use it.  His response was simply:
"There's a separation between academia and industry."  Schaeffer stated
that perhaps the programmers of top chess programs don't believe in
the potential of temporal difference algorithms in the chess domain.
Or, perhaps, they don't want to put the effort into them.

I believe Crafty is the strongest program in academia now.  If not,
certainly among the strongest.  So, Bob -- have you looked at TDLeaf
and found it wanting?  It's interesting (and perplexing) to me that
paper after paper praises the potential of TDLeaf, but it's _yet_ to
be used in the high end programs.  Knightcap was strong, but it's
definitely not in the top tier.

Maybe Tridgell/Baxter quit to soon, and Knightcap really could've been
a top tier program.  Or maybe the reason nobody is using TD is because
it's impractical for the large number of parameters required to be
competitive in chess.  Or maybe Schaeffer was right, and the commercial
guys just aren't taking TD seriously.



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