Author: Robert Hyatt
Date: 01:59:04 08/10/98
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On August 09, 1998 at 23:57:46, blass uri wrote: > >On August 09, 1998 at 23:28:43, Jouni Uski wrote: > >>Can any programming expert explain this: There are some simple positions, which >>Fritz5 is not able to solve because of null-move(as I have been told). But >>are they totally unsolvable even if I give Fritz enough time let's say one >>year?! > >I did not give fritz one year to run but I believe Fritz cannot solve them >and it is not a problem of time. >If there is no threat then fritz simply do not analyze so it cannot see. >There are positions other programs can solve in 1 second and fritz cannot solve >because it sees the result of 1 move is a draw and cannot see the result of a >second move is better because there is no threat in the second move. > >These positions are not common because fritz does not use null move in king and >pawn endgames and when there are queens in the board >position with no threat are not common. > >Uri >> >>Jouni Basically null-move fails whenever there is a zugzwang. Which means that not moving is the best move. There are few such positions when there are pieces on the board, but they do exist. And in such positions, each time such a situation arises, the null-move fails high, not because the position is good for the side on move, but because the position is so bad that doing nothing is actually the best move... and no amount of searching will get around that, unless the null-move algorithm is modified in some way... It is possible, however, to reduce the frequency of occurrences, but it means turning null-move off at selected nodes...
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