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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