Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: More information + a couple of diagrams

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?



This page took 0 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.