Author: José Antônio Fabiano Mendes
Date: 15:50:04 04/03/00
Go up one level in this thread
On April 03, 2000 at 18:45:27, José Antônio Fabiano Mendes wrote: >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]3kN3/4p1N1/8/8/8/8/4K3/8 w - - >================================= >White mates in 102 moves. >[D]8/7p/8/8/2NNk1K1/8/8/8 w - -
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