Author: Dieter Buerssner
Date: 12:44:09 08/03/01
A small question about chess rules. Assume the following position (which does not make any other sense, than to show my point): [D] 3kr3/8/8/8/3p4/8/4P3/3RK3 w - - 0 1 1. e4 Now black cannot capture ep. Then just some stupid moves: 1...Kd7 2. Ke2 Kd8 3. Ke1 Again the same postion as after 1. e4. 3...Kd7 4. Ke2 Kd8 Can at this point White claim a draw, by saying "I intend to move Ke1 - 3fold repetion"? I assume yes. If this is correct: Are you handling this correctly in your chess-engine? The reason why I ask. For the position after 1. e4 the engine may set the ep-square. I am doing this for Yace. It would be rather expensive, to check, if the actual ep capture is legal (at least, it would be expensive doing this in the search). At a later point, Yace will of course recognize, that the ep-capture is not legal, but then it is too late ... And a related question about Nalimov EGTBs. I have learned, that setting the ep square for the TB-probing in positions, where no ep capture is possible, returns invalid results. I recognized this in KNPKN. I earlier just set the ep-square after any double pawn push. This had now influence on the search/move-generation logic of my program. But probing of the TB with the ep-square set yielded wrong results. I fixed this. Now, I wonder, if the TBs will work correctly in the above scenario, when it really looks like the ep capture is possible at first sight, but it is not allowed, because the pawn is pinned. I think, the only available TBs, for this to occure are KXPKP for X=B,R,Q. I have neither of those, so I can't check. Regards, Dieter
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