Author: Uri Blass
Date: 12:16:06 09/01/02
Go up one level in this thread
On September 01, 2002 at 14:11:01, Gian-Carlo Pascutto wrote: >On September 01, 2002 at 04:40:52, Tony Werten wrote: > >>>>>- FP I don't believe in. You? >>>> >>>>FP by definition can only save nodes when it's incorrect, so I threw it out. >>> >>>I do not understand. >>> >>>Do you mean that pruning based on evaluation,remaining depth and other >>>conditions is not FP. >>> >>>If it is not FP then what is FP? >> >>I'm quite sure (from previous talks with Bas ) he was talking about futility >>pruning wich is wrong by nature. >> >>FP prunes the last move ( before quiescence ) when the score is a certain margin >>below alpha. >> >>Now suppose FP is right but we don't prune. What happens ? We go to quiescence; >>evaluate; get a score above beta; and cutoff. So no nodes saved. >> >>FP can only save nodes when we would otherwise spend time in quiescence; ie >>score is not above beta ie fp was wrong. >> >>People who report big wins with fp probably have an "inc(nodecounter)" in the >>top of quiescence, wich doesn't get called when pruning. >> >>Tony >> >>PS I'm talking about nodecounts here not time. > >The difference in time should be minimal as well. You're saving a call >to quiescence, and a lazy evaluation. Your lazy eval should be no more >than just calculating the material situation. The difference is that >futility pruning only does that calculation once. I do not have lazy evaluation and do not plan to have lazy evaluation(I prefer incremental evaluation) but I think that deciding for someone what the lazy evaluation should be does not make sense. The only clear thing is that the lazy evaluation should be clearly faster to calculate than the not lazy evaluation. Uri
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