Author: Robert Hyatt
Date: 19:47:37 01/06/04
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On January 05, 2004 at 19:24:31, Bas Hamstra 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. > >Here is what I tried (idea from Bruce I believe): > >Before you search all moves (after nullmove) you search all moves (unsorted) >with D-R and check if there is one and only one move with a score above alpha >*and* above Alpha-Margin. If so, in the normal search to depth D extend that >move. I did not do this in nullwindow searches, or else performance crashed. No >great results. In particular I didn't see much spectacular long pv's show up. > One addition I think Bruce and I both tested. What you are looking for is a quick fail-high on one move, while all others fail low on a much lower window to prove "singularity". However, if the first N moves (4 is what I think I last tried) all failed low, I quit, since this might be an "all node" where there can be no reasonable definition of "singularity". If you want more details, I can provide at least what I tried myself. BTW I don't think either of us searched "unsorted". We tried our normal move ordering so that the "4 move bailout" could be reliably used. >I am interested in refinements or other approaches. And are there good >testpositions to check the effect of SE? > > >Best regards, >Bas.
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