Author: Jeremiah Penery
Date: 22:32:29 04/03/00
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On April 04, 2000 at 00:00:41, KarinsDad wrote: >It occurs to me that the example that Jeremiah gave us in that thread could >still result in a loss for the KNP side of KNNPKNP. For example (and I did not >check this with tablebases, I am making an illustration here and hopefully, I >set it up correctly): > >[D]8/n1PK3p/k6N/8/6N1/8/8/8 w - - > >Now, even though this may result in a mate for white after c8(Q)+, it may take >more than 50 moves to do it. However, the idea is that the knight at h6 could >blockade the pawn until about move 40 or so, then it could come attack the king, >then when the pawn is pushed, it could go back and blockade again for a moment. >The 50 move counter would be reset since the pawn was pushed and then the knight >could come back to attack the king again. > >Now, this probably does not work for this particular example. I just put it here >to illustrate the idea. > >But it seems to me that the BEST play would take into account the 50 move rule >COMBINED WITH the shortest mate, even if that takes longer due to reseting the >50 move rule counter. > >If there are examples of this occuring within the tablebases (and I do not know >that for a fact since I do not have them), it would appear that the tablebases >are in reality a good tool, but a partially flawed tool (since it would be >extremely difficult for a program to determine that it is time to attack the >king with the knight, and oops, it is time to head back and blockade the pawn >again). > >KarinsDad :) I really need to try and find the relevant position from the game... Anyway, I know the Nalimov TBs do _NOT_ take into account the 50-move rule. I remember when someone posted a game and asked for analysis, to show whether black had a win or not, it would end up in a KNNKP which would be won in ~80 moves. However, the 'optimal' mate fell victim to the 50-move rule. It's possible that the program could simply be programmed that once it got near the 50-move barrier in a TB endgame, it would resort to search, trying to find a move that resets the counter while still remaining in a won position. Such a thing may not bee all too difficult to program, and it could help a lot, especially when _very long_ mates are possible, as in the new 6-piece TBs.
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