Author: KarinsDad
Date: 11:14:19 12/24/98
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On December 24, 1998 at 13:34:04, Roberto Waldteufel wrote: Roberto, You mention that if the null move search hits a zugzwang, the search is broken. But you do not mention how to fix it. I assume that if you could detect zugzwang (possibly by finding that all Ply x+2 moves have a lower score than their parent Ply x+1 move as indicated in my previous message), you could back out and re-search the Ply x+1 moves without the null move search. Would this method of detection and re-search work? And I am totally confused on how one would go about using multiple null move searches within a single path (do you alternate between sides or what, and what does this buy you?). Thanks, KarinsDad > >Hi KD, > >Basically you are taking a gamble that the position is *not* zugzwang whenever >you use null move. The speed-up is substantial, but if you do hit a zugzwang >then your search is broken completely (unless you are lucky and he PV is not >affected). This gamble is fairly safe in the opening and middlegame, but very >dangerous in the endgame when zugzwang is common, so normally we disallow null >moves when the material falls below some critical threshold. > >Hope this makes it clearer. >Merry Christmas >Roberto
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