Author: Omid David Tabibi
Date: 09:52:21 11/23/02
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On November 23, 2002 at 11:37:25, Martin Giepmans wrote: >On November 23, 2002 at 08:48:36, Omid David Tabibi wrote: > >>On November 23, 2002 at 08:45:00, Uri Blass wrote: >> >>>On November 23, 2002 at 08:11:37, scott farrell wrote: >>> >>>>Just after other people's thoughts. >>>> >>>>I think Omid's work overlooked the adapative null move searching many of us do, >>>>ie. transitioning from r=3 to r=2. >>>> >>>>I think adaptive null move tries to GUESS where to use r=2 to reduce the errors >>>>that R=3 makes. I guess it depends on how often this GUESS is correct, the cost >>>>of the verification search, and how long it takes the adaptive searching to >>>>catch the error at the next ply. >>>> >>>>Has anyone looked at setting the verification search to reduced depth of 2 >>>>(rather than 1)? obviously to reduce the cost of the verification search. >>> >>>Omid checked it but you also reduce the gain. >>> >>>I think that I will look for good rules when to do the verification search so >>>the cost will be significantly smaller but the gain is going to be the same in >>>at least 99% of the cases. >>> >> >>I'm currently working on other variations. The initial results are promising. >> >>>Uri > >I have done some tests with your method at greater depths. >At depth 12 vrfd R=3 still had an overhead (in terms of treesize) of about >25% compared to pure R=3. Of course verified R=3 will *always* construct a larger tree than standard R=3. However, starting from a certain depth, it will always construct a smaller tree than standard R=2. Take note, that while verified R=3 constructs a slightly larger tree than standard R=3, it has a superior tactical strength to even R=2 ! > >(my engine uses a simple Q-search that shouldn't give problems here) > >So the question is if your expectation that the treesize of R=3 and vrfd R=3 >converge at greater depths (> 11) really holds. > >Needs more testing, I think. > >Another point: >I would expect that vrfd R=3 becomes less safe at greater depths. >The subtrees in which you don't verify nullmove (after the verification) become >deeper and I see no reason - on logical grounds - why this shouldn't give safety >problems. >Even if R=3 and vrfd R=3 converge in terms of treesize, the safety (or rather >the lack of it) might also converge ... > None will converge. However, the deeper you go, the smaller will be the difference in tree size, and the greater the difference in tactical strength. >In any case, thanks for sharing. > >Martin
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