Author: Robert Hyatt
Date: 12:53:53 12/28/99
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On December 28, 1999 at 14:10:37, Gian-Carlo Pascutto wrote: >On December 27, 1999 at 13:38:29, Robert Hyatt wrote: > >>Here is what I think is the right way to do this, as was done in Cray Blitz >>and Belle: >> >>search the first move with a tight aspiration window. Search the rest with >>a null window. If one fails high, mark it as "best" but don't re-search it >>yet. If that is the only one that fails high, it is the best. If a second >>move fails high, re-search one with a wider window to get a real score, then >>search the second to see if if it fails high. If not, the first is the best, >>otherwise the fail-high move is the best. >> >>The only problem with this is that you can start a new iteration without a PV. >>If you use internal iterative deepening, this shouldn't be a problem. If you >>don't, it can cause problems... >> >>However, many hate getting a fail high without knowing whether the move is >>a centipawn better or a rook better. :) > >Well, thats seems quite logical to me. After all, how are you going to set the >bounds on your next interation's aspiration search if you don't have a score to >go with ? You'll almost certainly end up with a fail-high or fail-low again. > >-- >GCP Yes... although a fail high or fail low are easier to compute than a true score of course... but you can get into trouble. And most of the time you get the score anyway because you get more than one fail-high and have to resolve it. I didn't like it in Cray Blitz, but kept it for efficiency. The drawback is that if you stop on a fail-high move, you have no move to ponder. Crafty solves that by doing a search, but it was too complex in Cray Blitz so at times it would be idle when the opponent was thinking, something I didn't like much.
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