Author: Johan Melin
Date: 03:04:02 01/06/01
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On January 05, 2001 at 15:21:18, Severi Salminen wrote: >Hi! > >1.If I prune a move in normal search: if(material+gain(move)+FMARGIN<=alpha) >what should I assign to the best score so far? Material+gain, material+FMARGIN, >material+gain+FMARGIN or material only? Now I'm using material+FMARGIN but it >can't be right. Material+gain sounds right because that would be returned from >qsearch if stand pat fails high? In fail-hard alpha-beta, the correct value for a fail-low is alpha. However, if you are using fail-soft, you should return the best bound that you are confident in. In this case, that bound would be material+gain+FMARGIN. This is not an estimate of what the score will be, but an upper bound on how high the score might be. >2.I'm using now SEE and I wonder what is the "correct" value to return from >qsearch if I prune all captures: if(eval()+seescore(move)+MARGIN<=alpha)? Now I >just return alpha. If all moves result a score<=alpha should I return >eval+seescore or something else. Here as well, treat the pruned move as if it had the score eval+see+MARGIN, which is the best bound you get without search. If you return alpha you lose information about how bad this position is, and if you return eval+see the bound will often be to optimistic. /Johan Melin >I ask this because PVS or aspiration window search doesn't seem to like "wrong >values" > >Severi
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