Author: Omid David
Date: 15:20:51 07/11/02
Go up one level in this thread
On July 11, 2002 at 18:04:37, Uri Blass wrote: >On July 11, 2002 at 17:46:36, Omid David wrote: > >>On July 11, 2002 at 17:41:08, Uri Blass wrote: >> >>>On July 11, 2002 at 16:38:50, Omid David wrote: >>> >>>>As part of an extensive research (will be published soon), we tested null-move >>>>pruning with fixed depth reductions of R=2 and R=3 on about 800 positions of >>>>"mate in 4" (searched to depth of 8 plies) and "mate in 5" (searched to depth of >>>>10 plies). The results naturally show that R=2 has greater tactical performance >>>>(greater number of checkmate detection). >>> >>>This is not the right test. >>>It is clear that if you search to fix depth R=2 is going to be better. >>> >>>The question is what happens when you search for the same time. >>> >>> >>> However, we also conducted about >>>>hundred self-play matches under 60min/game time control between R=2 and R=3. The >>>>outcome is a rather balanced result (R=2 only a little better). Considering that >>>>the tests where conducted on a rather slow engine (100k nps), on faster engines >>>>R=3 is expected to perform better. >>> >>>I think that a better test should include different programs and not the same >>>program against itself. >>> >>>Another point is that R=2 and R=3 are not the only possibilities. >>>> >>>>So, apparently R=2 is not _by_far_ better than R=3 as some assume. >>> >>>I suspect that it is dependent on the program(results may be different for >>>programs with different qsearch and different evaluation). >>> >>>Uri >> >>I don't expect R=2 to gain more from greater speed than R=3. As a matter of fact >>as Dr.Hyatt recently mentioned with faster hardware in the future, R=3 might >>reach depths in which the total saving would be more significant than tactical >>deficiency (deeper search would compensate for it). In such cases one might even >>think of R=4 at some parts of the search tree (or as Dr.Hyatt just mentioned an >>adaptive R=3~4 value). > >I agree that R=3 and R=4 should be also considered. > >From my experience in GCP test suites at 5 minutes per move recursive R=3 got >the best results so far in GCP test suites(I do not know about games because I >did not test it for games at slow time control but I suspect that it is possible >that for movei R=3 may be even better than R=2 at the same time control). I think in blitz time controls R=2 will be by far stronger than R=3, since the search won't get deep enough and consequently: 1. R=3 won't save too much search effort in comparison to R=2 2. R=3 won't have time to search deeper to compensate its tactical deficiencies. But in deeper time controls especially in faster engines like Crafty, it'll perform better I believe. > >Note that the alternatives are not only R=2 and R=3 > >I suspect that starting with a small R in the first iterations may be even >better. > >You can increase R during the search. >There is no reason to do changes that do programs weaker at blitz on slow >hardware. > >Uri
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