Author: Robert Hyatt
Date: 13:01:17 11/17/04
Go up one level in this thread
On November 17, 2004 at 14:25:22, Uri Blass wrote: >On November 17, 2004 at 13:32:44, Robert Hyatt wrote: > >>On November 17, 2004 at 09:31:53, Alessandro Scotti wrote: >> >>>On November 17, 2004 at 08:27:47, Jan K. wrote: >>> >>>>Under winboard/arena which of the following positions should be claimed(/can be >>>>claimed) as drawn by insufficient material-KBKN, KBKNN, KNNKNN? I thought that >>>>KBKN can be claimed as a draw, but once this position happened under Fritz GUI, >>>>my engine claimed draw and stopped playing but GUI still expected me to move and >>>>my engine lost on time. Thx. >>> >>>According to FIDE rules: >>> >>>"The game is drawn when a position is reached from which a checkmate cannot >>>occur by any possible series of legal moves, even with the most unskilled play." >>> >>>If this is followed strictly, there are not many possibilities! That said... I >>>think I also have the KBKN bug! :-) >> >> >>It is easy to construct a position where KB mates KN. It seems to be impossible >>to construct a position where that mate position can be forced. Calling it a >>draw is perfectly fine IMHO. > >It seems that mate with the bishop against the knight cannot be forced but mate >with the knight against the boshop can be forced(from root position that has >more pieces). > >White cannot prevent that mate in the following diagram so claiming a draw only >because the position in the board is KN vs KB is generally wrong. > >[D]1r6/8/8/8/8/k2B4/p2n4/K6R w - - 0 1 > >1.Bc2 Rb1+ 2.Rxb1 axb1Q+ 3.Bxb1 Nb3# > >Note that I see that Crafty has no problem to see the mate in this line so it >does not return a draw for KB vs KN and stop to search. > >If the engines have no bugs it may be logical to adjudicate games of KB vs KN as >draw after there is position with KB vs KN when there is no mate in 1 but not to >do it only based on the fact that the position is KB vs KN. > >Uri In Crafty, if the search finds a mate, it is taken. If this gets to the evaluation code, it is declared a draw...
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