Author: Robert Hyatt
Date: 05:29:42 03/17/98
Go up one level in this thread
On March 17, 1998 at 07:44:31, Bernhard Bauer wrote: >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. > While I have solved *some* null-move problems, as Amir said later, the above position is *not* a null-move problem. I, too, have code that says that a king and single knight can not possibly win. Because I have never had a position where it was possible in a real game. As A result, I would call KN vs anything as no better than 0.00, and possibly lower depending on what the other side has. I can't solve the above test position either... unless I disable the quick "instant draw" check in "RepetitionCheck()" where I catch it. Then I find it instantly... >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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