Author: Dieter Buerssner
Date: 14:17:43 10/10/02
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On October 10, 2002 at 07:16:27, Nagendra Singh Tomar wrote: >In ur example; you should note that when we are searching for the opponent's >best reply for d4 we always have alpha and beta (calculated till the first >subtree e5 is fully evaluated)in hand. If we find any of the opponent's reply to >be better than e5 (and asusming that e4 was THE best move), the score of the >reply WILL be more than the beta set by e4 hence it will fail-high and we will >not update PV. You are correct, and the example I gave was bad. Other posters explained it better. To my excuse, I might say: For my engine the example was mor or less correct, because I also update "PVs" (which may be be called refutation variation) when outside of the alpha-beta window (so for a fail low node, whatever the fail soft alpha beta loop reported as best move, for fail high node, the move that returns a score >= beta). I use this "refutation PV" to help moveordering, for example in the case where a reasearch from zero window search is needed. Regards, Dieter
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