Author: Severi Salminen
Date: 02:20:01 01/12/01
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>It used to bother me a lot too. Then Bruce Moreland explained that search >inconsistencies (which this is about) are unavoidable if you use hashtables and >pruning based on alpha/beta values. To quote him: "If you use a hashtable, you >have dirt in you hair. If you do nullmove, you are buried in mud". Pretty clear >:-) If you think about it, it's logical. Nullmove makes errors. With different >windows different branches will be pruned resulting in different errors. Enough >to affect the rootscore. I saw it all the time. Bruce too. When I hacked the >ExChess code to see if it had the same behaviour a year ago the answer was: yes. It truly is logical but looks odd when you first see it: fail low, and then score doesn't chance at all...so stupid. >If you turn nullmove and hash off the problem should not occur at all, or else >you have a bug. I don't use aspiration anymore, as soon as I can measure it >matters a lot I will put it back in. At this point I am not convinced, though >most do use it. I don't have hashtables yet, but turning nullmove off makes the problem disappear. Do you think that this nullmove problem might occur even without hashtables (for me it does occur - only in this position though)? The reason I'm asking this many times is that I _really_ don't want to try to spend hours of finding a bug which doesn't actually exist. Thanks for all the help, Severi
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