Author: Ricardo Gibert
Date: 22:37:20 10/07/00
Go up one level in this thread
On October 08, 2000 at 01:27:15, Dave Gomboc wrote: >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 Very interesting. Is there a download article on this? I'm curious if this a practical algorithm, why it is not being used in programs. Does it include positions where pawns can move forward? Or only positions where they are blocked?
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