Author: James Robertson
Date: 02:29:55 08/20/99
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On August 20, 1999 at 05:08:06, Bruce Moreland wrote: > >On August 20, 1999 at 04:59:26, James Robertson wrote: > >>When my program spots a mate, if the position is, say, mate in 5, it may give a >>score "mate in 10", and then the next move "mate in 6", and then "mate in 3", >>and so on. Sometimes the "mate in x" will increase to "mate in x+y". >> >>When a mate is spotted, my program never fails to mate, and it seems to do it in >>the minimum moves possible. I am still worried; I don't think I have noticed any >>other programs doing this. >> >>I adjust my mate scores to reflect the node (if (score > MATE/2) score -= ply), >>but I may be goofing this up. Is this tied in with my problem in the post below >>this one? If anyone can help, I would really appreciate it. >> >>James > >When you want to store a mate score or bound in the hash table, adjust the score >so that it is a bound, if you can. > >For instance, if the score is mate in 6, store it as >= mate in 300 or whatever. I am not completely sure I understand. Say I find a position is +mate in 6, would I score it with the flag 'lower bound' and a score of mate in 300, instead of an 'exact' flag with a score of +mate in 6? > >There are some dumb cases like if you are failing high or failing low, where you >may have to just laugh and not store anything. Err.... I don't understand here either. How would I decide not to store anything? > >This won't hurt performance, I think, and will guarantee that you can never get >a bogus mate score bug ever. > >If the bound is not enough to cause a cutoff, chances are that you are either >winning big or losing big, so who cares. For me, it is a major struggle just to figure out how this whole hash thing works with alpha-beta. I _think_ I get the gist of what is happening, but may be completely off. Does this mean that if we look up +mate 300 (actaully it is +mate in 6, but we adjusted it) is < beta, then we are winning so much it doesn't matter? > >Please resist the temptation to implement this and then assume/wish that you've >fixed the problem you mention in the other thread. Ok! James > >bruce
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