Author: Bernhard Bauer
Date: 04:44:31 03/17/98
Go up one level in this thread
On March 14, 1998 at 15:34:19, Sylvain Renard wrote:
> During the World Micro Computer Chess Championship in Paris,
>Amir Ban told us that his program didn't use the null move technique.
>So I was rather surprised that Junior 4.6 could not find the winning
>move in this position: White Kh3, Ne7, pawns g3,h4; Black Kf3,
>Ne5, pawns g6,h5; black to move. 1...Ng4!
> This test was first used for computers in 1982 (!) by M. Pierre Nolot
>(Europe Echecs n°286 Octobre 1982).
> Fritz 2, 3 and 4 are also unable to find the solution because there
>are using the null move technique and there is a zugzwang in the main
>line.
>But Frans Morsch worked well and Fritz 5 now plays the good move.
> Can Amir Ban explain to us what is going wrong with Junior and this
>test? Thank you!
You shouldn't blame the null move technique. It's the impementaton of
null move!
Some time ago crafty failed for this problem too. It's no. 11 on Pierre
Nolot's
set. This caused some difficulties, as the benchmark was not runnable,
because
of a log(sum of times) term.
However Robert Hyatt has overcome this problem and finds Ng4 in 1 sec on
my PPro200.
There are, however, positions where crafty fails due to null move.
One example:
End game study of A. Troitzky: 4B3/8/6N1/5p2/1r4p1/6pk/7b/4K2Q w
Here a position where rebel is said to fail:
Ortueta - Sanz, Madrid 1934
8/pR4pk/1b6/2p5/N1p5/8/PP1r2PP/6K1
Crafty needs only 38 sec to find the solution.
Here a position where rebel fails in mating mode:
Mate in 3 by Dr. Ado Kraemer
+---+---+---+---+---+---+---+---+
8 | | | | | B | | K | |
+---+---+---+---+---+---+---+---+
7 | | | | | | | P | |
+---+---+---+---+---+---+---+---+
6 | *P| | | | | | | |
+---+---+---+---+---+---+---+---+
5 | *K| | B | | | *P| | *P|
+---+---+---+---+---+---+---+---+
4 | | *P| | N | *P| P | *B| |
+---+---+---+---+---+---+---+---+
3 | *B| | | | *R| | | *Q|
+---+---+---+---+---+---+---+---+
2 | | | | | *P| | | |
+---+---+---+---+---+---+---+---+
1 | | | | | Q | | | |
+---+---+---+---+---+---+---+---+
a b c d e f g h
Rebel gives the wrong key move, whereas crafty solves it correct in
usual playing mode.
Enjoy this problem by solving it yourself,
or
use rebel and find out why rebel is wrong!
Here the position in FEN: 4B1K/6P/p/k1B2p1p/1p1NpPb/b3r2q/4p/4Q w
Kind regards
B. Bauer
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