Author: Robert Hyatt
Date: 20:59:25 09/16/99
First, a little background. I have been doing 'outside passed pawn' scoring for years now, because I got tired of seeing Crafty lose endings where it was a pawn up, and it traded down to the point where it was a king and pawns vs king and pawns ending, where the opponent had an outside passed pawn that made it an easy win... OK... that was fairly easy to code using bitmaps... and it has worked well. But once you get past that hurdle, you begin to see endings where you trade down to a pawn-up ending, but your opponent has a queen-side majority that turns into an outside passer outside the search horizon, and the same issue comes up again. I am working on addressing this now, and am looking for a discussion on what might be the best way to do this. I have completed a fairly accurate 'candidate passed pawn' analyzer. It is in the EvaluatePawns() code so that it is all hashable and won't cost a fortune. All it does is simply look at each pawn that has no enemy pawn in front of it, and decides whether pushing that pawn can make a passer or not. Again, not hard using bitmaps, and in studying the results, it looks reasonable. My intent is to use this in the absense of any outside passed pawns for one side, to see if it has any potential outside passed pawns on that side of the board. And for the usual 3 vs 2 queen-side majorities, it works cleanly and accurately. But what about 4 vs 3? Where the passer ends up on the d-file, which might not be far enough away to cause problems. Or what about 3 vs 3, where one side has pawns on a-b-c, the other side has pawns on b-c-d, and both end up with a passer although the abc passer will be more distant. I guess my question is, has anyone given any thought to this? Or is anybody even dealing with pawn majorities at present? I tend to not actually call this majority code any longer, because it is _really_ candidate passed pawn evaluation instead... My intention is to recognize that if the kings are on g1/g8, and white has the a-b-c pawns and black just has b-c pawns, that this is a nearly winning position. I am going to do just like I do with outside passers, that is, have their value go up as material goes down, as they don't mean much with queens and pieces on the board... Any comments, suggestions, ideas, etc? Obviously necessary, yet I don't see any evidence that any program does much with this excepting for deep blue... Bob
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