Author: Robert Hyatt
Date: 11:32:09 06/22/98
Go up one level in this thread
On June 22, 1998 at 12:15:25, Amir Ban wrote: >On June 22, 1998 at 10:02:42, blass uri wrote: > >>The position 3k4/2p1p1p1/p1P1P1Pp/P6P/4K3/8/8/8 >>white to move. >> >>every human can understand it is a draw but my programs cannot evaluate >>the position as 0.00 >>Is there a program that understand it is a draw? >>( it is enough to use an hash table of 36*9*2=648 positions) >> >>Uri > >This is a good example to see what your hash table can't do for you. > >The problem is that all the positions here evaluate the same. None of them are >obviously drawn or obviously won, so the only way the search can find a draw >score is to find a repetition or 50 moves in the PV. White cannot be forced to >make a repetition, so the only hope is to search this to 100 ply, but this takes >too much time. > >Amir maybe not, in fact. I get to 60 plies (max depth I can search to) in 7 seconds total time. But I won't call this a draw until 3 reps or 50 moves goes by. I can modify this to see the draw pretty easily, by giving black a bishop that is trapped behind the pawns. Then, because black is ahead in material, white will try to repeat, and black doesn't have nearly so many squares to reach as does white. And 60 plies picks up the draw trivially...
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