Author: Sune Fischer
Date: 03:03:36 12/13/02
Go up one level in this thread
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. 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. >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. Perhaps it is possible to prove some lemma that will make things easier. -S.
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