Author: Peter Fendrich
Date: 14:51:17 10/10/02
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On October 10, 2002 at 17:17:43, Dieter Buerssner wrote: >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. Will this really help? The fail low node will not produce anything useful and the fail high node move will be kept in the hash table so when researching it will be there anyway. wont it? Peter >Regards, >Dieter
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