Author: Uri Blass

Date: 13:06:39 01/31/02

Go up one level in this thread

On January 31, 2002 at 15:26:40, Roy Eassa wrote: >On January 31, 2002 at 15:19:16, Uri Blass wrote: > >>On January 31, 2002 at 12:41:11, Roy Eassa wrote: >> >>>On January 30, 2002 at 18:52:06, Vincent Lejeune wrote: >>> >>>>On January 30, 2002 at 18:07:38, Chessfun wrote: >>>> >>>>>On January 30, 2002 at 17:18:21, Roy Eassa wrote: >>>>> >>>>>>On January 29, 2002 at 16:13:45, Roy Eassa wrote: >>>>>> >>>>>>>in the following position Black can play ...Re6 and be in >>>>>>>very good shape (certainly not behind). However, Fritz 7b evaluates this >>>>>>>position as being better for White by about 5 pawns: >>>>>>> >>>>>>>[d] 8/8/1p1r1k2/p1pRN1p1/P3K1P1/1P6/8/8 b - - 0 2 >>>>>> >>>>>>Re: So is this a BUG in Fritz 7b -- something that should be fixed? Something >>>>>>that could easily be fixed without negatively impacting anything else to any >>>>>>measurable degree? >>>>> >>>>> >>>>>Not just Fritz 7b, infact most Fritz versions see white clearly winning. >>>>> >>>>>Sarah. >>>> >>>>Yes, simply because : >>>>1)white is in zugzwang >>>>and >>>>2)Fritz use null-move >>>>and both are not compatible with each other. >>> >>> >>>But other programmers' engines use null move and they do NOT have the same >>>problem with this position (due to refinements in their null move handling, as I >>>understand it). >>> >>>Thus this is essentially a Fritz BUG that can be fixed, thereby making Fritz >>>stronger (IMO). >> >>No it is not. >>It is a design decision of the Fritz programmers to use slightly different null >>move algorithm. >> >>many of the other programs also blunder before this move and Crafty blundered in >>the game because of it's null move algorithm. >> >>Uri > > >I have never seen a position where a move immediately wins a piece and changes >the evaluation from -5 to +1, yet a top program cannot see it. > >Until now. > >That should be classified as a bug, IMHO. Here is an anlaysis of shredder 2 plies before on p200 Shredder5.32 cannot see the winning material move except depth 1 when shredder believes that Nxd5 is losing a piece. It is not winning a piece but I am almost sure that it is possible to change the position such that shredder is going to miss winning a piece. New position [D]8/8/1p1r1k2/p1pPN1p1/P3KnP1/1P6/8/3R4 b - - 0 1 Analysis by Shredder 5.32: 1...Rxd5 2.Rxd5 Ne2 3.Rxc5 bxc5 4.Nd7+ ± (0.83) Depth: 1/2 00:00:00 1...Rxd5 2.Rxd5 Nxd5 3.Kxd5 c4 +- (2.10) Depth: 1/2 00:00:00 1...Rxd5 2.Rxd5 Nxd5 3.Kxd5 c4 +- (3.80) Depth: 1/2 00:00:00 1...Nxd5 2.Rxd5 Re6 3.Kd3 Rxe5 4.Rd6+ Re6 5.Rxe6+ Kxe6 6.Ke4 Kd6 7.Kf5 b5 8.axb5 c4 9.bxc4 a4 10.Kxg5 +- (3.50) Depth: 1/2 00:00:00 1...Nxd5 2.Rxd5 Re6 3.Kd3 Rxe5 4.Rd6+ Re6 5.Rxe6+ Kxe6 6.Ke4 Kd6 7.Kf5 b5 8.axb5 c4 9.bxc4 a4 10.Kxg5 +- (3.50) Depth: 1/2 00:00:00 1...b5 2.axb5 a4 +- (2.31) Depth: 1/2 00:00:00 1...b5 2.axb5 a4 +- (1.76) Depth: 1/2 00:00:00 1...b5 2.axb5 a4 +- (1.76) Depth: 1/2 00:00:00 1...Ke7 2.Nc4 Rh6 ² (0.60) Depth: 1/2 00:00:00 1...Ke7 2.Nc4 Rh6 ± (0.83) Depth: 1/2 00:00:00 1...Ke7 2.Rd3 ± (0.79) Depth: 2/4 00:00:00 1...Ke7 2.Nc4 Nh5 3.gxh5 Rd8 ± (1.05) Depth: 3/6 00:00:00 1...Ke7 2.Nc4 Rh6 ± (1.35) Depth: 3/6 00:00:00 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 ± (0.83) Depth: 3/6 00:00:00 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 ± (0.83) Depth: 3/6 00:00:00 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 ± (0.83) Depth: 4/8 00:00:00 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 ± (0.83) Depth: 5/10 00:00:00 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 ± (0.83) Depth: 6/12 00:00:00 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 ± (0.83) Depth: 7/14 00:00:00 1kN 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 ± (0.83) Depth: 8/16 00:00:00 2kN 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 ± (0.83) Depth: 9/18 00:00:00 3kN 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 ± (0.83) Depth: 10/20 00:00:01 4kN 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 ± (0.83) Depth: 11/22 00:00:01 5kN 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 ± (0.83) Depth: 12/24 00:00:01 7kN 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 ± (0.83) Depth: 13/25 00:00:01 11kN 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 4.Nxb6 Nd4+ 5.Kf2 Re2+ 6.Kf1 ± (0.78) Depth: 14/26 00:00:26 770kN 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 4.Nxb6 Nd4+ 5.Kf2 Re2+ 6.Kf1 Re4 7.Nd7+ Ke7 8.Nxc5 Rxg4 9.Kf2 Kd6 ² (0.70) Depth: 15/27 00:01:43 3473kN 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 4.Nxb6 Nd4+ 5.Kf2 Ke7 6.Re1+ Kd8 7.Rxe8+ Kxe8 8.Ke3 Nxb3 9.Kd3 Ke7 ± (0.79) Depth: 16/28 00:04:45 9204kN 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 4.Nxb6 Nd4+ 5.Kf2 Re2+ 6.Kf1 Re4 7.Nd7+ Ke7 8.Nxc5 Rf4+ ± (0.80) Depth: 17/29 00:10:16 22197kN 1...Rd8 2.Nc4 Re8+ 3.Kf3 Ne2 4.Nxb6 Nd4+ 5.Kf2 Re2+ 6.Kf1 Re4 7.Nd7+ Ke7 8.Nxc5 Rf4+ ± (0.72) Depth: 18/30 00:23:32 48689kN 1...Rd8 2.Rh1 Nxd5 3.Rh6+ Kg7 4.Rg6+ Kf8 5.Re6 Nc3+ 6.Kf5 b5 7.axb5 Nxb5 8.Kxg5 Nd4 9.Rb6 Ke7 ² (0.70) Depth: 19/31 01:25:41 188426kN 1...Rd8 2.Rh1 Nxd5 3.Rh6+ Kg7 4.Rg6+ Kh7 5.Re6 b5 6.axb5 Nc3+ 7.Kf5 Nxb5 8.Kxg5 Nd4 9.Re7+ Kg8 10.Rb7 Rf8 ± (0.83) Depth: 20/32 02:29:33 331868kN 1...Rd8 2.Rh1 Nxd5 3.Rh6+ Kg7 4.Rg6+ Kf8 5.Nc4 Nc3+ 6.Kf5 b5 7.axb5 Nxb5 8.Kxg5 Rd5+ 9.Kf6 Rd3 10.Nxa5 Nd4 ± (0.85) Depth: 21/33 04:49:30 638246kN 1...Rd8 2.Rh1 Nxd5 3.Rh6+ Kg7 4.Rg6+ Kh7 5.Re6 b5 6.axb5 Nc3+ 7.Kf5 Nxb5 8.Re7+ Kg8 9.Nd7 Nd4+ 10.Kg6 c4 11.bxc4 Ne6 ± (0.92) Depth: 22/34 09:07:25 1191993kN 1...Rd8 2.Rh1 Nxd5 3.Rh6+ Kg7 4.Rg6+ Kf8 5.Nc4 Nc3+ 6.Kf5 b5 7.axb5 Nxb5 8.Kxg5 Nd4 9.Rb6 ± (1.05) Depth: 23/35 25:17:48 3275496kN

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