Author: Robert Hyatt
Date: 08:53:09 05/29/99
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On May 29, 1999 at 10:53:50, James T. Walker wrote: >Hello, >I have a question about Crafty/Winboard. One of my complaints about winboard is >that it does not show the number of moves to mate by Crafty. Can the score >which is like 327.44 be interpreted to "Mate in N"? This is when Crafty is >using the tablebases and has definitely found mate. >Jim Walker in a raw sense, yes... in crafty MATE=32768. - scores mean 'mated' while + scores mean "mating". IE any + score means crafty sees mate while - scores means that it sees that it is getting mated. In 'analysis mode' +scores means white is mating, while -scores mean black is mating. To compute the distance to mate, just take (32768 - score) / 2 ie here are some numbers: 32766 = mate on the move (or mate in 1 where the move given mates, so mate in 1 and mate are the same, since the score is effective _before_ the first move is played). -32767 means 'mated' now. IE I have no legal moves in this position. if you add 2 (or -2) at a time, you get successively higher mate in N/mated in N scores. -32765 is mated in 2 -32763 is mated in 3 +32764 is mate in 2 +32762 is mate in 3 etc... note that mated in N scores are odd, mate in N scores are even, because the score is always MATE-ply. At odd plys, the side on move is the program, and it is getting mated. Crafty corrects the sign in analysis mode to make the scores +=good for white, for simplicity. I am one day going to make _all_ displayed scores +=good for white, and -=good for black, to eliminate _all_ ambiguity.
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