Author: Robert Hyatt
Date: 06:45:45 12/09/00
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On December 09, 2000 at 05:56:25, Georg v. Zimmermann wrote: >>> >>>But this wont happen if your margin is large enough. As large as your largest >>>position scores. As explained by Ernst. Very simple. And accurate. >> >> >>Yes... but if the margin is "big enough" then you don't have futility pruning, >>either. That is the problem. And if you eliminate _one_ node from the tree >>search, you stand the chance of perturbing the score that eventually backs up >>to the root of the tree, due to the hash table. >> >>The problem with "big enough" is that for some programs, "big enough" might be >>a pawn or two. For other programs it might be way more than a queen. Such a >>window effectively disables futility pruning. For those that want to produce >>very large positional scores. > >What I am doing is to set value = fmax = eval(); instead of materialeval(). That >way your margin can be the maximum eval change in 1ply only. This obviously only >works if your eval() is very fast. If not, you can try to write another >fasteval() function which only uses those eval parts than can get very big, king >safety for example. I got good results with that. > >Regards, >Georg v. Zimmermann The problem is that an eval can change a _lot_ in one ply, for some programs. IE mine could change by at least a queen for the right kind of capture. Or the right kind of pawn move.
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