Author: Christophe Theron
Date: 11:27:44 12/26/97
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On December 26, 1997 at 12:26:23, Don Dailey wrote:
>Perhaps they are doing heavy pruning on the computers moves? If you
>modify the selectivity such that much heavier pruning takes place
>on the computers side you might arrarnge extra depth that results in
>play that is safe but not opportunistic for the computer.
>
>I remember Richard Langs programs USED to have the characteristic
>that they would see anything you could do to them. In some experiments
>me and Larry Kaufman did, it would quickly see that you could win
>a piece and avoid the loss. But if you forced the piece losing move
>and let it think for the winning side, it could not find the win without
>a very long think! Very strange. But this was the best program in the
>world and pehaps still is.
>
>But this makes some sense to me. I don't think a single chess game has
>ever been won without an error on the losing side. If your program
>NEVER made an error (you wish!) it would never lose (unless of course
>the opening position is a loss for one side or the other.)
I have tried recently to modify Tiger this way. First, I changed the
time allocation policy to allow the program to play only when the last
move in the main line was a computer's move. This allows the program to
detect more deep threats. Second, I made a more agressive selection on
Tiger's move. So he could miss a combination for him, but wouldn't miss
an opponent' s combination.
In average, this new version shows deeper lines (1 ply more).
I let the program run a long self play against the previous version
(exactly the same program except for the two above changes). The rate of
play was 5mn/game on a P100, 4Mb hash.
Result: no improvement at all. The score was very close to 50%.
In addition, the new version performs poorly on combination tests.
I've made several others tests with differents changes, trying to prove
the idea was good, but I didn't succeed.
Still I believe that the idea of being very cautious and conservative
has some value. I think I didn't catch the right way to do it.
Christophe
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