Author: José Antônio Fabiano Mendes
Date: 15:45:27 04/03/00
Go up one level in this thread
On April 03, 2000 at 15:27:16, Robert Hyatt wrote: >On April 03, 2000 at 10:54:21, KarinsDad wrote: > >>On April 03, 2000 at 06:10:21, Jeremiah Penery wrote: >> >>>There is a problem with tablebases. >>> >>>No, they don't produce wrong answers. And no, they don't make engines play >>>weaker. The problem is that engines would rather be -9 and not in TBs than see >>>mate against itself and be in TBs. I have one good example, from a game my >>>modified Crafty played on ICC, and I may try to find it, if possible. But I do >>>remember what happened: >>> >>>I had something like a knight and a pawn, and my opponent had 2 knights and a >>>pawn, about to promote. I had the choice to let him promote, and have a score >>>of about -9. I would easily lose. My other choice was to sacrifice my knight >>>for his pawn, and enter a lost KNNKP endgame, somewhere around Mate in 75. I >>>would not easily lose this, unless my opponent had the TB, in which case it >>>could be a draw by 50-moves. >> >> >>Excuse me, but what am I missing? >> >>Isn't a KNNKP ending almost always a draw (assuming nothing special) if the side >>with the pawn wants it to be? Cannot the side with the pawn force the draw >>(regardless of 50 move rule) since KNNK is a draw? >> >>What do you mean by a "lost KNNKP endgame"? >> >>KarinsDad :) >> >> >>> >>>I forced Crafty to enter the KNNKP endgame, and got a draw out of it. >>> >>>Had I not done so, Crafty would have preferred the -9 score, which would >>>eventually lose very easily due to the opponent's new Queen. >>> >>>I'm wondering if anyone has experimented with making the engine prefer difficult >>>lost TB endings over easily lost non-TB endings, especially in cases like KNNKP. >>> I think this could at least turn a few lost games into draws (as it did for >>>me), and possibly something better could come of it if some interesting new >>>ideas were formulated based on this. >>> >>>Jeremiah > >\ >Many KNN vs KP endings are wins for the two knights. The problem with KNN vs K >is that the king can't force mate directly... the usual attempts generally >stalemate the opponent one move before mate can be delivered. Hence the >importance of the pawn. The stalemate doesn't happen as he can push the pawn, >and then get mated the next move... > >I have seen mate announcements of > 100 in this ending... at blitz time >controls on ICC Two interesting KNNKP endings: a)White plays and Black draws. [D]3kN3/4p1N1/8/8/8/8/8/4K3 w - - b)White mates in 70 moves. [D]3kN4/4p1N1/8/8/8/8/4K3/8 w - - ================================= White mates in 102 moves. [D]8/7p/8/8/2NNk1K1/8/8/8 w - -
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