Author: J. Wesley Cleveland
Date: 21:28:05 07/28/02
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On July 28, 2002 at 13:02:01, Robert Hyatt wrote: >On July 27, 2002 at 15:06:23, J. Wesley Cleveland wrote: > >>On July 25, 2002 at 20:13:45, Robert Hyatt wrote: >> >>>On July 25, 2002 at 19:24:06, J. Wesley Cleveland wrote: >>> >>>>I see that crafty does not store lower bounds of MATE-n in the hash table, >>>>rather changes them to MATE-300. Bob wrote that he had search instabilities >>>>before he did this. Normally, this does not matter, but I think it makes crafty >>>>considerably slower in finding mates, as it only gets cutoffs on exact scores. >>>>Do other people have experience in this ? >>> >>> >>>Note that all this does is slightly decrease search efficiency. I do store >>>_exact_ mate scores as they should be stored. I store "bounds" that are based >>>on MATE as MATE-300. The penalty is _very_ small unless you have a position >>>where almost everything leads to a forced mate of some sort... >> >>The place where I notice it is in engame analysis with EGTBs, where after a long >>time the PV is scored as Mate in 38 or so, and then it takes a *very* long time >>to prove the other root moves are worse. >> >>A related question: >>If the score in the hash table is MATE-300 and this would cause a cutoff, >>shouldn't you cut off even if the draft is not deep enough ? > > >I could but I don't. That would prevent finding a _shorter_ mate the next >iteration. But wouldn't you only care about a shorter mate if the _value_ would not cause a cutoff ?
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