Author: Uri Blass
Date: 14:01:43 03/22/03
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On March 22, 2003 at 16:26:30, Albert Bertilsson wrote: >On March 21, 2003 at 09:33:31, Uri Blass wrote: > >>On March 21, 2003 at 09:09:05, Albert Bertilsson wrote: >> >>>aybe I misunderstood your previous post, but what I intended to clarify was the >>>kind of situations that caused Sharper to search too deep. This happens without >>>the use of extensions of any kind. There just seems to be a few positions that >>>are searched very deep, and that's the reason for having the MAXPLY limitation. >>> >>>/Regards Albert Bertilsson >> >>It seems that I did not understand your post >>You wrote: >> >>"Both sides have a piece that they need to protect or defend, if they don't the >>loose almost immediatly. So the line is a series of moves from both sides trying >>to vary their game to push the inevitable draw forward." >> >>I understood from it that you extend in case that the side to move has a piece >>under threat. >> >>If you do not extend then I do not see why the fact that both side has >>a piece that they need to protect is relevant. >> >I just described the type of position that caused the trouble I don't know why >these positions search very deep, I just noticed that they do. > >I'm happy if it doesn't makes any sense to you because that probably means that >it isn't something that I should feel bad about not understanding. > >/Regards Albert No I say that I do not understand because your explanation means that you do extensions(without extensions you should never get long lines if you have no bugs). If you do not do extensions and have long lines then it means that you have a bug. I think that it is a mistake to use hash tables for pruning at the level of your program. First thing you should use them only for order of moves and find that they are productive and only later you can think about using them for pruning. Movei still does not use them for pruning and I am interested more in other improvements that I can get(I believe that a big progress can be made without doing it). The only case when I use hash to save search today is when I get a draw by repetition and the hash keys tell me that it is a repetition so I return 0. It is also not easy to implement using hash tables for pruning together with other ideas that I use and plan to use in a productive way. Uri
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