Author: Edward Screven
Date: 08:41:22 05/15/99
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On May 15, 1999 at 08:34:20, William Bryant wrote: >You now make your first root move, and search with alpha now equal to -beta, >and beta equal to -alpha, which makes beta equal to INFINITY. >If you call a null move at this point, the null move window is >INFINITY, INFINITY +1 which obviously does nothing but return a score of >INFINITY which is greater or equal to beta ..... null move heuristic in a nutshell: don't search this node if a null move made by the side to move results in a score >= beta at a reduced search depth. when testing this condition you should a search window (beta-1,beta). so if beta is INFINITY, the null move window should be (INFINITY-1,INFINITY), not what you described above. now obviously, if beta is INFINITY the null move heuristic should never cut off, since a search should never result in a value as high as INFINITY. in my own program i actually don't try a null move if beta is INFINITY. this probably doesn't have any measurable effect though, since beta should be INFINITY at very few nodes. - edward
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