Author: blass uri
Date: 13:44:28 01/26/99
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On January 26, 1999 at 08:46:19, Robert Hyatt wrote: >On January 25, 1999 at 22:48:02, Nuno Maltez wrote: > >>Hi, >> >>I've stumbled on what looks like a silly problem (bug) using Fritz 5.32 and >>endgame databases. I don't know if this has been mentioned before, but I've >>don't remeber reading anything about it neither here nor in rgcc (I don't read >>every post though), so here it goes: >> >>Take the following position (Black to move): >>White: Kg6, Rh4, Ph3 >>Black: Kg8, Rf7 >> >>I was playing black (we got here from an endgame position taken from a textbook) >>and moved 1...Rg7+. Fritz using the databases evaluated all continuations as (0) >>and played 2.Kh6. I replyed 2...Rh7+ and here Fritz evaluated again all moves as >>(0) and played the unbelievable 3.Kg6?? losing the rook and the game. After >>3...Rxh4 it returned to the normal engine and quickly realized white is lost. >> >>Has anyone faced this problem before? I'm using a Fritz 5.32 update downloaded >>from Chessbase's site late December. I've not tested other positions, but it >>looks like the program's not noticing the difference between a draw and a loss >>(database problem?). Is this some configuration problem or what? >> >>Thanks in advance, >>Nuno > >I didn't look at the specific position, but this problem has been long known in >fritz, because it uses Ken Thompson's 'distance to conversion' databases. IE it >tries to choose the move leading to the shortest 'conversion' to a fewer number >of pieces that is drawn, but it doesn't pay attention to the actual board >position. I think that the problem is that Fritz does not believe KRP can lose against KR and evaluates draw in positions that the KRP is losing. I did not see this problem in other endgames in the tablebases of fritz5(for example KQP vs KQ or KQ vs KR) I do not think that it is a problem of Ken Thompson's distance to conversion because you can use 2 numbers(distance to conversion and result of the game). The problem is also only when KRP is losing against KR so they can simply use search in cases of drawn KRP vs KR. There is no chance they will lose if they search in KRP vs KR instead of using tablebases and there is a better
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