Author: Andrea Griffini
Date: 05:00:24 06/17/03
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On June 16, 2003 at 18:43:19, Peter Fendrich wrote: >One thing. >You have to be careful here with the sign and who is to move... >I suppose that you are using minimax and probes the moves without >actally making them. >First, the scores you get is one level down and the sign should be >reversed before used. Second, You have changed side without making the move on >board. The side to move has to be reflected in some way when you're probing. If >you are XOR-ing some value in order to separate between black and white to move >you mustn't forget to do that here even if the board position itself >doesn't say so. I jumped on the chair shouting "that's it" ... but when I checked my code I found indeed that the hash probing was done after making the move so the color is correct, and even the value sign is correctly negated when compared to current alpha-beta window. The reason the moved is played is that to do the sorting I actually perform the moves on the board to see if they're giving check (checks are pushed for early examination) and just after that I added the hash probing that if found successful (i.e. allowing a beta cut) just cleans things up a bit and quits immediately. Now I've changed a few things (especially in the quiescience search part) and I should check that forward hash probing again. One bad thing with chess programs is IMO that's quite easy to have them *seriously* buggy but still somewhat working. Andrea
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