Author: Uri Blass
Date: 03:29:40 12/13/02
Go up one level in this thread
On December 13, 2002 at 06:03:36, Sune Fischer wrote: >On December 12, 2002 at 23:49:59, Uri Blass wrote: > >>On December 12, 2002 at 17:17:04, Dann Corbit wrote: >> >><snipped> >>>>[D]k7/P2ppp2/K7/8/8/8/7P/8 w - - 0 1 >>>> >>>>I can see mate in 5 without calculating all the tree >>>> >>>>1.h4,2.h5 3.h6,4.h7,5.h8R# >>>> >>>>a stupid computer program(and I believe that all of the available programs are) >>>>need to calculate a lot of lines(1.h4 f5,1.h4 f6,....) >>> >>>You have to calculate the square root of the nodes of the tree. Not the full >>>tree. >> >>No >> >>In this case there is a simple plan 1.h4 2.h5 3.h6 4.h7 5.h8Q# >> >>It is easy to see that black can do nothing against it without calculating. >> >>I need only to look at class of positions and not on specific positions. >> >>Here is the proof of the mate in 5. >> >>1.h4 black has 3 pawns at f,g,h files but the pawns did not go after f5,g5,h5 >>2.h5 black has 3 pawns at f,g,h files but the pawns did not go after f4,g4,h4 >>3.h6 black has 3 pawns at f,g,h files but the pawns did not go after f3,g3,h3 >>4.h7 black has 3 pawns at f,g,h files but the pawns did not go after f2,g2,h2 >>5.h8R# >> >>I do not know of computers that calculates in that way but it is theoretically >>possible to do it. > >I think you are using some knowledge here, that white is not mated in steps >1.-4. If I'm not mistaken you have to prove that 1.h4 f5 does not end the game. It seems obvious to be that after h4 when only the black pawns moves white is not in check. After h4 I know that there may be black pawns only in 3 of the squares(h7,h6,h5,g7,g6,g5,f7,f6,f5) I do not need to check every possibility to know that when the pawns are only in these squares the white king is not in check. The proof is simple 1.The only pieces that black has except king is pawns. 2.The only place for pawn to threat check is g7 3.No black pawn can move to g7 conclusion: There is no way for black to threat check without promotion of the pawns when the white king does not move. > >Thus you have to examine that none of black's moves will mate white or stall >mate black. This requires explicit search of each move and would give you a >square root tree search. I proved that none of the black moves are going to mate white. It is clear that when there is no check none of black moves are going to stalemate white because white can move the pawn. It is clear that none of the black moves are going to stalemate black because there is nothing that can prevent one of the black pawns to go forward when it did not promote because white does not move with the pieces to that file. > >>If chest can do it then it can be faster but I have not simple idea how to >>detect patterns like this pattern. > >They do simple algebra on pawn races. But that is because the programmer assumes >the knowledge that we need to promote to win. It is not always true, you can >mate with a pawn. In theory you can do it but it is clear that none of the moves that black has in the position that I posted can do it. Uri
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