Author: Angrim
Date: 18:28:52 03/08/02
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On March 08, 2002 at 01:18:25, Uri Blass wrote: >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 See http://www.cs.vu.nl/~victor/thesis.html also do a search on google for "proof number search" Angrim
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