Author: Robert Hyatt
Date: 10:02:01 07/28/02
Go up one level in this thread
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.
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