Author: Dave Gomboc
Date: 22:27:15 10/07/00
Go up one level in this thread
On October 07, 2000 at 22:29:44, Ricardo Gibert wrote: >On October 07, 2000 at 19:32:18, Vincent Diepeveen wrote: > >>On October 07, 2000 at 15:16:17, Peter McKenzie wrote: >> >>>The position where the solution is most in doubt: >>> >>>[D]2k2K2/8/pp6/2p5/2P5/PP6/8/8 w - - >>> >>>The authors say that after 1.Ke8 Kc7 2.Ke7, black draws by 2...b5 with a >>>stalemate motif after 3.Ke6 b4 4.a4 Kb6. >> >>nice motif for humans. peanut for the computer to see. >>however, after 1.a4 i get a 0.00 score from diep initially, >>now there are sure some bugs in this version, as i'm busy rewriting >>its hashing to 64 bits (which asks for bugs of course), but 0.00 is >>pretty hard. it is basically doubting between 0.50 and 0.00 on most >>plies. where the stalemate position is 50 moves of shuffling around >>with king and score +1.31. this version not showing +3.x scores weirdly. >> >>what is the win with a4 which i'm missing? and 20 plies of search too, >>which is hard to believe in this position. with all 3 vs 2 egtb attached >>and 20 plies of search with the white king already penetrated i either >>expect to see +mateXX or see many pawns go or see draw score if it's >>a draw. Now i get a slight draw score depending upon depth it is 0.00 or >>+0.50 for white. That's not very convincing. >> >>>Of course white can vary, and they quote: 4.axb4 cxb4 5.Kd5 a5 6.Kc5 a4= >>> >>>Or: 2.a4 b5 which is supposed to be drawn too. >> >>>I haven't checked these lines thoroughly, but quickly playing some of them vs my >>>program suggests they are probably correct. Certainly its possible there is a >>>mistake though. >>> >>>The other controversial positon: >>> >>>[D]8/1k6/p4p2/2p2P2/p1P2P2/2P5/P1K5/8 w - - >>> >>>Kc1 is analysed using the 'theory of corresponding squares', something I don't >>>really understand :-) I haven't analysed this one at all, I will just quote the >>>main variation: >> >>i have wasted a full evening to go to a meeting where the writers >>about the 'corresponding square' theory were there. >> >>it's all big nonsense. the problem is to figure out what the corresponding >>squares are. it's like saying: "find best move M and play perfect >>chess". Now the problem is to find move M. So is the problem to >>find the corresponding squares. There is no algorithm for it at all. >>After wasting hours of talk to the authors who themselves aren't strong >>chessplayers at all, they couldn't give any algorithm for it, and it >>all appeared to come down to how well you can define squares as being >>the corresponding square! >> >>>1.Kc1! Kc7 2.Kd1! Kd7 3.Ke1 Kc7 4.Kf2 Kd8 5.Ke2 Ke8 6.Kd3 Kd7 7.Ke3 Kd6 8.Ke4 >>>"(forcing the pawn to advance)" a3 9.Kd3 a5 10.Kc2! a4 "The posiiton on the >>>Q-side is blocked; a quadratic system with non-ambiguous rear (711) now >>>operates." Go figure! 11.Kc2! Ke7 12.Kd3 Kc6 13.Ke2 Kd6 14.Kf2 Kd7 15.Ke3 Ke7 >>>16.Kf3 and wins >> >>that's 16 moves. I'm searching 40 plies. that's 20 moves. So i see >>4 moves deeper as this. Also i have made afew moves and then also searched >>40 plies. that's like 23 ply in the diagram position. So obviously this >>trick isn't the problem here! >> >>>I didn't play thru. that variation, but clearly its at least 31ply and white >>>hasn't even captured a pawn yet! Let me see, finished with white K on f3, so it >>>needs another 3 moves at the very least to capture c5 so this problem looks like >>>it is at the VERY least 34ply deep and probably more. >> >>I searched if i count the moves made first with it 44 plies or something >>and don't see a win at all. >> >>>cheers, >>>Peter > >If you are really interested in the theory of corresponding squares, you may >want to have a look at the book, "The Final Countdown" by Willem Hajenius & >Herman van Riemsdijk. > >As for translating it into a computer comprehensible algorithm, I don't think it >is practical. Your opinion notwithstanding, Murray Campbell did it over ten years ago. :-) Dave
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