Author: martin fierz
Date: 05:30:20 07/05/01
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On July 05, 2001 at 07:47:43, Vincent Diepeveen wrote: >On July 04, 2001 at 07:01:55, martin fierz wrote: > >>On July 04, 2001 at 05:41:22, Dan Andersson wrote: >> >>>ProbCut and MultiProbCut: >>>http://www.neci.nec.com/homepages/mic/publications.html >>>AFAIK this is the canonical source. >> >>thanks! i had missed the multiprobcut paper there. >> >>has anyone ever tried this in chess? >> >>cheers >> martin > >Yes it didn't work here. Apart from that it gametree technical >seen is dubious to do, it's reduction factor is too big. > >Both for my draughts program as well for my chessprogram it didn't work. > >Fullwidth search is way better for draughts. I get 40 to 60 ply >fullwidth in endgame anyway (and still it cannot win won endgames). > >Best regards, >Vincent hi vincent, what do you mean by "it's reduction factor is too big"? you can make probcut more or less aggressive by changing the probe depth and by changing the cutoff value. obviously some settings will make the program play much worse, while sensible settings make it play better. at least for my checkers program that is true - and it's not just a small improvement... (works for othello too, which is a much more complex game than checkers). i assumed that the problem of probcut with chess is that there is a king, which makes the game hard to predict. for instance, you can sacrifice a large amount of material for a mating attack, and the pruning algorithm isn't allowed to prune there, else you don't see it. in checkers, things are very different, because there is no king. it is usually very stupid to sacrifice material. therefore forward pruning gets good results. i'm surprised (and i can hardly believe!) that it doesnt work in 10x10 draughts! do you really use no pruning at all? can kings in draughts move like queens in chess or like kings? cheers martin
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