Author: Stefano Gemma
Date: 01:52:30 04/18/04
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On April 17, 2004 at 08:16:21, Joachim Rang wrote: >This position is an easy mate in 4: > >[D]6Q1/8/8/7k/8/8/3p1pp1/3Kbrrb w - - 0 1 > >Certain engines however have problems to see the mate and return instead a draw >score. So ie Crafty. > >I think it is related to nullmove, since the solution involves a zugzwang for >the black side and since it's so many material on board most engines will use >nullmove in this position. However I thought Nullmove will produce a reduction >rathern than a complete cutt-off and hence the solution should be found a few >plies later. Or did I understand the mechanism of Nullmove wrong? > >I know that this position is not of any interest if it comes to playing >strength, but it is rather funny to watch certain engines reach depth 20 quickly >while being unable to spot the mate. > >regards Joachim Thanks to this position, i've found some bug in "Freccia" ;-). My program doesn't use null-move, so, after corrected the other bugs, it find the mate in just 609 milliseconds: ply 8: val=63.981003 nodes=1205272 msec=609 n/s=1979100 Q.g8g7 As you can see, the number of visited nodes is very high, this is because i don't use null-moves nor hash-tables. Ciao!!! Stefano Gemma
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