Author: KarinsDad
Date: 21:55:40 08/05/99
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On August 05, 1999 at 23:02:00, Robert Hyatt wrote: [snip] > > >that isn't the case I am looking at. I have a position that is a mate in 220 >plies, or 110 moves. If I play it 'perfectly' I will make only one pawn move >at move 90, but I will draw because at move 50 no pawn pushes have been played. >In this position, I can push a pawn at ply=20, but if I do so, I won't be able >to push it again until ply=130. And that is 10 plies too deep and again I draw >if I push it at 20. But if I wait to ply 40 to push it, I can still push it >again at ply=130, and now I am 'home free' with no chance of a draw, although >the total mate is probably going to be much longer than 220 plies, since I had >to avoid the optimal path to avoid the 50-move draws... > >That is the problem I don't see a way to solve, ever... > Well, this problem cannot be solved with the current tablebases. And, since it cannot be solved with them, the best you can do is attempt to accidentally find a solution. In the case you specify, the program would find a potential solution at ply 20, but as it got further down the search, it would find that this does not solve the problem and a draw will result. The problem you specify could be solved with a tablebase that had win preserving moves (for 50 move rule only) in it. The reason is that a win preserving move by definition is one that resets the counter and leads to mate. It does not matter how many moves down below it the mate occurs since you know by definition that somewhere down the 100 ply you will either mate or you will find another win preserving move. Note: a win preserving move would have the distance to reseting the counter, not the distance to mate. So, the problem is solvable (at least for those positions where it CAN be solved). For positions where it cannot be solved, it doesn't matter. They are already a draw and they will stay that way unless the opponent blunders. KarinsDad :)
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