BUG by Crafty 20.14 w32?

[Edward German]

BUG by Crafty 20.14 ?

PGN (On Playchess.com played, My Nick is Wolkenlos):

[Event "Wertungspartie, 16m + 0s"]
[Site "Maschinenraum"]
[Date "2007.12.30"]
[Round "?"]
[White "Wolkenlos, Rybka 2.3.2a 32-bit"]
[Black "Ultima, Crafty 20.14 w32"]
[Result "1-0"]
[ECO "D47"]
[BlackElo "2368"]
[Annotator "0.00;-0.16"]
[PlyCount "109"]
[EventDate "2007.12.30"]
[TimeControl "960"]

{Crafty 20.14 w32: 17.2 ply; 1.037kN/s AMD Athlon(tm) XP 3000+ 2171MHz, (1
threads), Solist.ctg, oreDeviceObjects} 1. d4 {B/0 0} d5 {B/0 0} 2. c4 {B/0 0}
c6 {B/0 0} 3. Nf3 {B/0 0} Nf6 {B/0 0} 4. Nc3 {B/0 0} e6 {B/0 0} 5. e3 {
(Bg5) B/0 0} Nbd7 {B/0 0} 6. Bd3 {(Qc2) B/0 0} dxc4 {B/0 0} 7. Bxc4 {B/0 0} b5
{B/0 0} 8. Be2 {(Bd3) B/0 0} Bb7 {B/0 0} 9. O-O {B/0 0} a6 {B/0 0} 10. e4 {
B/0 0} c5 {B/0 0} 11. d5 {(e5) B/0 0} exd5 {B/0 0} 12. e5 {(exd5) B/0 0} Ne4 {
B/0 0} 13. Nxd5 {B/0 0} Nxe5 {B/0 0} 14. Nxe5 {B/0 0} Qxd5 {B/0 0} 15. Qxd5 {
B/0 0} Bxd5 {B/0 0} 16. Rd1 {B/0 0} Be6 {B/0 0} 17. a4 {B/0 0} Bd6 {B/0 0} 18.
Bf4 {B/0 0} O-O {B/0 0} 19. f3 {B/0 0} f6 {B/0 0} 20. Nd3 {B/0 0} Bc4 {B/0 0}
21. axb5 {B/0 0} Bxb5 {B/0 0} 22. Bxd6 {(fxe4) B/0 0} Nxd6 {B/0 0} 23. Nxc5 {
B/0 0} Bxe2 {B/0 0} 24. Rxd6 {B/0 0} Rfd8 {B/0 0} 25. Rxd8+ {B/0 0} Rxd8 {B/0 0
} 26. Kf2 {B/0 0} Rd2 {B/0 0} 27. b4 {(b3) B/0 0} Bc4+ {
Wolkenlos,Rybka 2.3.2a 32-bit bietet Remis -0.16/13 28} 28. Kg3 {0.00/20 71}
Rd6 {-0.08/14 1} 29. Ne4 {(Kf2) 0.00/18 20} Rd4 {-0.17/14 29} 30. Nc5 {
0.00/20 10} Kf7 {-0.31/13 14} 31. Nxa6 {(f4) 0.00/19 20} Rd6 {-2.73/14 33} 32.
Nc5 {(Kf2) 0.79/19 53} g5 {1.19/12 32} 33. Ra7+ {(Kh3) 0.97/18 74} Kg6 {
0.93/14 30} 34. Rd7 {(f4) 0.99/19 13} Rxd7 {1.85/16 28} 35. Nxd7 {0.87/23 15}
Kf5 {1.84/16 11} 36. Kf2 {0.86/23 26} Bb5 {1.88/16 0} 37. g4+ {(Nc5) 0.97/24 49
} Ke6 {1.96/17 27} 38. Nc5+ {0.99/24 24} Ke5 {2.09/17 2} 39. Ke3 {1.27/24 13}
h6 {1.96/17 16} 40. Nb3 {1.45/23 11} Be8 {2.08/17 23} 41. Nd4 {1.97/25 18} Bg6
{2.39/16 28} 42. Nf5 {(b5) 2.78/24 33} Be8 {3.08/17 43} 43. Nxh6 {2.96/26 4}
Ba4 {3.05/16 25} 44. Nf5 {2.96/23 11} Bd7 {3.58/16 22} 45. f4+ {4.66/22 7} Kd5
{3.58/15 13} 46. h3 {4.72/23 4} Ba4 {4.12/16 16} 47. Ng3 {5.09/23 3} Bc2 {
4.56/16 18} 48. Nh5 {(b5) 5.11/23 36} Ke6 {4.19/16 94} 49. b5 {5.09/20 14} Bb3
{4.73/16 3} 50. b6 {5.09/17 103} Bd5 {5.96/19 0} 51. Ng3 {5.13/16 38} Bc6 {
6.21/17 0} 52. Ne4 {5.59/14 7} Ke7 {6.65/17 9} 53. fxg5 {6.06/16 3} fxg5 {
8.34/18 14} 54. Nxg5 {6.06/16 0} Bb7 {9.26/18 16} 55. Ne4 {
(h4) Ultima,Crafty 20.14 w32 abbandona (Lag: Av=0.58s, max=1.9s) 7.18/16 32}
1-0

Position after Move 31 (White):

Wolkenlos,R - Ultima,C, Wertungspartie, 16m + 0s 2007

[D]8/5kpp/N4p2/8/1Pbr4/5PK1/6PP/R7 b - - 0 1

Analysis by Rybka 2.3.2a mp 32-bit :

31...Lxa6 32.Txa6 Txb4 33.Ta7+ Kg6 34.f4 Tb3+ 35.Kf2 Tb2+ 36.Kf3 Tb3+ 37.Kf2 Tb2+ 38.Kf3
= (0.00) Tiefe: 19 00:00:06 1477kN

This Position is a clear draw "out book", but Crafty played here now 31...Rd6 {-2.73/14 33}???

Is that a BUG by Crafty?

[bob]

I can't reproduce it. Here all I see is Bxa6 with a score almost exactly zero...

[Mike S.]

From the cb-native version of Crafty 20.14:

Analysis by Crafty 20.14:

31...Bb5 32.Nc5 Rxb4 33.Ra7+ Kg8 34.Re7 Rb2
= (0.24) Depth: 4/8 00:00:00
² (0.50) Depth: 6/10 00:00:00 14kN
31...Bxa6 32.Rxa6 Rxb4 33.Ra7+ Kg6 34.Rd7 h6 35.f4 f5 36.h3
= (0.15) Depth: 6/10 00:00:00 33kN
= (0.05) Depth: 16/21 00:01:06 176mN, tb=55

Always 31...Bxa6 from ply 6 to 16. - This version doesn't have the "w32" attached to the name, so I think that it is possible that the WinBoard version was used via Wb2Uci (although I don't think that would explain the problem).

The cb-version supports multi-pv so we can see if Rd6 appears among the best lines:

Analysis by Crafty 20.14:

1. = (0.06): 31...Bxa6 32.Rxa6 Rxb4 33.Ra7+ Kg6 34.Rd7 f5 35.h3 Rb2 36.h4 Re2 37.f4 Rc2 38.Kh3
2. ± (1.01): 31...Be2 32.Nc5 Rxb4
3. ± (1.03): 31...Rd2 32.Nc5 Rb2 33.Ra7+ Kg6
4. ± (1.07): 31...Bb5 32.Nc5 Rxb4 33.Ra7+ Kg6 34.Rb7 h5
5. ± (1.39): 31...g5 32.Nc5 Kg6 33.Rb1 Bb5 34.Ne6 Rd2 35.Nc7 Bd7 36.h3 f5 37.b5 f4+ 38.Kh2 Bf5 39.Re1

Not among the best five after depth 14 was completed. - Maybe this player is using a modified version of Crafty.