Author: Uri Blass
Date: 22:18:25 03/07/02
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On March 07, 2002 at 16:44:42, Angrim wrote: >On March 06, 2002 at 12:00:02, Miguel A. Ballicora wrote: >>Interesting. My program Gaviota finds Mate in 15, with the same sequence >>of moves in 18 seconds on a PIV 1.4 Ghz. Also, at ply 6 and I am very happy with >>that. The interesting part is that Gaviota requires ~2Mega positions >>where CM requires only 100K. In this particular position CM's tree is >>20-fold leaner! I will have to work hard on trimming the fat! > >Or, you could just add a proof-number search stage. This type of >position is very easy for proof-number search. > >pn-search on athlon 1.2ghz: >fen: 7k/2p3p1/4Q2p/p3n3/2pBP2P/2P3P1/1r2q3/5RK1 w - - 0 1 >proved that move f1f8 wins, 14.5 turns >PN:17176 evals, 1260 expands, 0.06 seconds > >Perhaps the most interesting part of this is that my pn-searcher has >no chess-specific knowledge other than how to generate legal moves >and score a mate position. I expect that someone who is good at >chess could write a version that is much better by writing an eval that >measures how close to being proven each leaf node is. I just use >the game-independant measure of counting the legal moves at each >leaf node. Can you explain what is proof number search and what is the difference between it and singular extension. This position is easy to solve with singular extensions because in every move black has a single reply to prevent mate(and in most of the cases there is only one legal move or only one legal move to prevent mate in 1 when the only exception is 3...Kxf6 when black has the alternative 3...Kh5). I also see that you evaluate 17176 nodes. I am interested to see the full tree. What is your order of moves? Do you start with moves that reduce the number of legal moves of the opponent. Does it mean that the first moves to search for white are 1.Rf8+ and 1.Qg8+ By this logic after 1.Rf8+ Kh7 you have 3 candidates(2.Qg8+,2.Qg6+,2.Rh8+) After 2.Qg8+ Kg6 you have Qf7+ first because Rf6+ gives black 2 replies. Uri
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