Author: Uri Blass
Date: 00:10:34 07/26/03
Go up one level in this thread
On July 26, 2003 at 03:00:00, Uri Blass wrote: >On July 25, 2003 at 19:44:43, Sune Fischer wrote: > >>On July 25, 2003 at 19:24:21, Eran wrote: >> >>>On July 25, 2003 at 17:50:21, Ernst Walet wrote: >>> >>>>This afternoon my account on the chessbase server played a game against Rebel >>>>12. To my astonishment Rebel missed a mate in one, and got mated right away. >>>>Any thoughts on this, Ed? >>>> >>>[D]8/8/6p1/6k1/3p2P1/4b2Q/4Bq2/7K w - - 0 151 >>> >>>If Fritz 8 or Crafty 19.03 plays the same game instead of Rebel 12, Fritz or >>>Crafty will play the same problem as Rebel 12. Please see below. >>> >>>So, do Fritz and Crafty have a bug for a long time? >> >>I suspect most engines has that bug, including mine. >>I've known about it for over a year, but have decided not to fix it because I >>can't find a way to do it. >> >>The reason is the engine makes the 50th move, checks the 100 ply counter and >>returns the draw score. >> >>To fix it, the engine needs to check for check mate _before_ it checks the >>counter, but most engines can't do that staticly, they have to search another >>ply to see the mate. > >No >There is a more simple solution. > >If counter=100 the engine check for checkmate before it decides that it is a >draw. > >If counter<100 you do not need to do it. > >I do not do it in that way and I check for checkmate at every node first. >Thanks to my legal move generator I do not need to search another ply but only >to generate a move if I want to verify no checkmate. > >Uri I can add that even if you need to search then searching one ply in your draw detection function only in case that the counter equal to 100 is not a big price. Uri
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