Author: Uri Blass
Date: 23:21:10 10/19/00
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On October 19, 2000 at 22:23:39, Christophe Theron wrote: >On October 19, 2000 at 16:31:38, Howard Exner wrote: > >>On October 18, 2000 at 14:14:20, Uri Blass wrote: >> >>>On October 18, 2000 at 12:34:42, Ricardo Gibert wrote: >>> >>><snipped> >>>>The algorithm to determine whether this type of position is drawn is quite >>>>simple. With the h-pawn, Black draws if the K can get into the four corner >>>>squares g7,g8,h7,h8. Otherwise, the outcome is not assured. Note, it is not >>>>enough for the King to get in front of the pawn as the following position >>>>illustrates: >>> >>>I can give another rule: >>>Blacks draw if it is black to move and the distance between the black king and >>>the corner in king moves is smaller than the ditance between the corner and the >>>white pieces except the bishop(white king in king moves and white pawn in pawn >>>moves) >>> >>>If it is white to move then use distance-1 instead of distance for white. >> >>This is very useful, I have many endgame books and I've never seen this >>description. It's one thing to point out where a program goes wrong and quite >>another to offer a solution in programmable language, like you have done. >> >>I think we all would like to see programs have a good routine to solve this >>scenario. > > > >You can count on me. I'll integrate this rule in Chess Tiger and Gambit Tiger as >soon as it is confirmed that I can use it even when white has several pawns on >the A or H file. > > > > Christophe It is simple to confirm it because of the following facts. 1)If the black king is in one of h8,g8,h7,g7 nothing can stop it from a draw and the number of pawns of white is not important. 2)If the black king is not in h8 then the black king always control black squares that are closer to the corner. 3)Assume it is black to move and black king is not in the corner My rule says that the black king is closer to the corner than the white king and the white pawns(the distance of pawns is in pawn moves so a pawn in h2 is the same as a pawn in h3 for calculating the distance). fact 2 means that black can control squares that are closer to the corner and that white cannot see(the bishop cannot see them because they are not in the right colour and the other pieces cannot see them because the distance in king moves is at least 2 and if the pawn is at h2 the distance in king moves is even 3 and the pawn cannot close the gap). 4)Assume that it is white to move. White cannot get closer to the corner with the king and the pawns by more than one step and my rule says that the difference in the distance is at least 2 so after white moves the black is still closer to the corner by at least one step and can continue the trip to the corner. Uri
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