Author: Sune Fischer
Date: 09:15:18 08/02/03
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On August 02, 2003 at 11:12:29, Tony Werten wrote: >>To summarize, a score can be considered "exact" only if it has been achieved >>independent of alpha and beta bounds. This is the case only if we are at a leaf >>node with full evaluation, or other node with alpha < value < beta. > >Or when a checkmate score is returned or a drawscore or .... This is not true. Consider a case where beta<=0, the first move you search bring back a draw score (say, forced repetition). Now you fail high without checking the rest, but you could have had a mating move or another winning line you didn't search. So it will just be a lower bound. Mate scores are another matter I think. >Sorry if I tell you something new, this is old stuff. > >When not doing any extensions ( not realistic but anyway) the values returned >from the last 2 plies from normal search are exact. (As was published 15 years >ago) I don't believe that, and I think my example above shows it. -S. >Tony >
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