Author: Bas Hamstra
Date: 08:46:50 12/27/99
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>I've tried adding null-moves as well, but haven't been very succesful. I >need some more to go on before I can get it right, but I can't find good >examples or descriptions of them. So far what I've tried is to try a >null-move before doing any real moves at a certain level of the tree, and >searching the null-move to the same depth as usual; my problem is that I >don't know what to do with the returned score. From what I gathered one >should create a cut-off when the score is 'not so good' even while doing >two moves in a row.. it didn't work for me though. It was far slower (1.5 >times) with the same results, and only a few dozen null-move cutoffs at >6 plies orso. When I increased the cut-off point by half a pawn in favor of >more null-move cut-offs all I got was a bunch of very bad moves. About nullmove: you just treat a "pass" as a normal move, and try that first. Normal moves are searched Depth deep, but a nullmove you search Depth-R deep, where R is typically 2. Now if the returned score is >= Beta you just return Beta, like normal. There is your cutoff. Idea is simply that if YOU do nothing (refuse to move, pass) and the score for doing nothing is *still* fabulous, the position is probably so good that you can do a beta cutoff on the base of a shallower search than normal. Regards, Bas Hamstra.
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