Author: David Blackman
Date: 18:05:41 01/22/00
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On January 22, 2000 at 11:33:58, José Carlos wrote: > Sorry, I forgot to say that I test my prog usually at blitz time controls. At >15 to 30 minutes a game, ply 7 usually is searched. At longer time controls I >have no time to test it, but I'm quite sure each new ply costs a lot more than >the previus (branching factor is about 5). Actually branch factor 5 without null move is pretty good. Maybe your move ordering is ok after all. But you can reduce the branch factor quite a lot with null move. A few people are getting about 3 with null move. > Anyway, my move generation is slow, because I wrote it from scratch, using a >programming "understandable, but not efficient". But I'll try to improve it > when I have a better understanding of searching techniques. > What confuses me is how old programs in very slow hardware could play a so >reasonable game. I am guessing a few well chosen extensions, probably some pruning, and well tuned eval functions. That was enough to avoid making too many blunders that B players could see. Of course they were much weaker tactically than programs on modern hardware, but they mostly avoided the "ugly" blunders. > About quiescence, you are right. More or less halve of the nodes searched are >in quiesce. I probe hash table in quiesce, but I'm sure my pruning is not >enough yet (only beta cutoffs). This can be reduced. One way is SEE pruning. Done carefully it might get you a factor of 2 speed up. It will occasionally cause you to miss tactics right at the end of the search, but not very often.
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