Author: Robert Hyatt
Date: 13:24:07 01/06/04
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On January 06, 2004 at 14:58:38, Anthony Cozzie wrote: >On January 06, 2004 at 14:32:58, Slater Wold wrote: > >>On January 05, 2004 at 08:48:23, José Carlos wrote: >> >>> Hi, I'd like to try singular extensions in my program. I've been trying to >>>think about it and all my tries so far result in worse performance. After some >>>web search I haven't been able to find anything but the general idea described. >>> Is there any good description somewhere? Some pseudo-code? I guess there must >>>be something interesting in the archives but I can't download all of them. >>> Thanks in advance, >>> >>> José C. >> >>SE and nullmove do not mix. And that's straight from Hsu. From speaking with >>him (via e-mail), I gathered that this would be his approach using nullmove, and >>I tried it in Crafty with very nominal success: > >they seem to work just fine in Ferret, arguably the strongest tactical program >out there. > >anthony Yes, but Ferret is not using Hsu's Singular Extension algorithm. not even close. Bruce is using a "SE approximation" that works very well, but it is not to be confused with what Hsu defined as singular extensions. I did the full DB implementation in Cray Blitz, and using non-recursive null-move R=1, it seemed to work pretty well. I have tried it more than once in Crafty, and it simply did not work reasonably whatever I tried. I've not decided that it is hopeless, but I have not played with it further in at least a couple of years now... I came to the same conclusion that somehow, null-move with bigger R values simply doesn't work very well. You extend, but null-move reduces the depth and things get lost in the middle.
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