Author: Rafael Andrist
Date: 12:29:52 11/15/01
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On November 15, 2001 at 14:52:01, Dieter Buerssner wrote: >>>[D] 8/8/6p1/6Q1/2K4p/6kP/5p2/8 b - - 0 55 > >Perhaps a naive idea would be: Dectect the cases of drawn Q vs. P (R or B-P on >7th rank and some rules for K positions). If all pawns of the Q-side are >blocked, it gets tricky. When from no blocking pawn a check can be given, or >the promotion square can be controlled, give the P on 7th the value of the Q. >It is of course still no guarantee for draw, because the Q side may be able to >force the promotion, exchange Qs and have a won pawn endgame. There are also problems if the pawns are not blocked. If you add an extra pawn to some drawn KQ-KP positions, black loses because of Zugzwang. >Perhaps a table with all such blocked pawn positions. Or some special table >base. > >Perhaps also a special search rule, although this won't be easy. When I play >against Yace in the above position after about 20 moves, I get a draw score. >When I go back, immediately a draw score is seen for any move almost until back >to the position (Yace remembers the positions together with search depth and >score, that where analyzed). Only at one point, where the move Qxg6 was, this >capture will be avoided, again with a bogus high score for white. When I do >again about 10 moves forward I see the draw score again. No I can go back until >the root, and the draw score will be seen there. This is a totally mechanical >manner - so it should be possible to do this automatically. I think, >essentially some sort of tablebase will be built for this position. Such a search algorithm would certainly be very good, not only for this case, but also for tactical middlegame positions. This would be very difficult to implement and require also a huge amount of theoretical work. Some pruning ideas which are easier to implent: - prune all lines where the defending side loses the essential pawn - prune all lines where the defending king clearly leaves the draw area of the appropriate KQ-KP endgame. With clearly I mean it would be necessary to give the king one ply more "radius", because the other pawns may block the queen to give an immediate check. regards Rafael B. Andrist
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