Author: Robert Hyatt
Date: 07:05:04 03/10/01
Go up one level in this thread
On March 10, 2001 at 03:34:19, Uri Blass wrote: >On March 10, 2001 at 02:55:29, Dann Corbit wrote: > >>On March 10, 2001 at 00:26:57, Michael Fuhrmann wrote: >> >>>[D] 8/8/7P/5kP1/5P2/r7/5K2/8 b - - 0 114 >>> >>> >>>Crafty scores this as -3.26 for white on my computer, yet it seems to be a draw. >>>I don't have all the 5-piece tbs. Is that the problem? >> >>I have the complete 5 piece tablebase file set. It does not seem to help much. >>However, it is clear that it is a draw. The output of the chase below is rather >>amusing. We might call it "I'll get that f4 pawn if it's the last thing I do!" >> >>Past the last actual search depth in plies, for each new search, it always ends >>in Kxf4. But each time we go one more ply (when we have actually examined the >>consequences of that horizon capture) it gets pushed out. It is clear that this >>is a draw. > >It seems that the problem is that Crafty does not look at the tablebases in the >last ply. >Maybe probing the tablebases everywhere can help Crafty to get more realistic >evaluation because it is not going to have wrong evaluation for KR vs KPP >endgames and evaluation for KR vs KPPP endgames is going to be closer to draw. > >Uri It isn't quite the "last ply". It is the first ply of the q-search, and I don't probe there as it is too expensive. Which means the goal of the search becomes "push the capture off to the q-search where I won't realize it is a draw." I have seen this in rare positions before... :)
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