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Subject: Re: Ugly bug in Phalanx XX

Author: Dusan Dobes

Date: 05:44:19 02/18/99

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On February 18, 1999 at 07:37:40, Frank Schneider wrote:

>On February 18, 1999 at 05:13:54, Dusan Dobes wrote:
>
>>I suggest upgrading Phalanx to version XXI.  Phalanx XX has an ugly
>>bug in the static evaluation that make it drop all it's material
>>in most engames with outside passed pawns.  It was detected by
>>Zeke Smigel who was running Phalanx on ICC, this is the critical
>>position: 8/6k1/6b1/3P2P1/6R1/2N1q3/1P3RK1/8 w - - 0 51  Rf7+??
>
>There was another position in the winboard-tournament, I think in this
>game:
>
>[Event "WinBoard 4.0.0, Turnier 3"]
>[Site "Trier/Hamburg"]
>[Date "1999.01.23"]
>[Round "7.1"]
>[White "Phalanx"]
>[Black "Gromit"]
>[Result "0-1"]
>[ECO "C01"]
>[WhiteElo "2437"]
>[BlackElo "2441"]
>[PlyCount "134"]
>[EventDate "1998.??.??"]
>
>1. e4 e6 2. d4 d5 3. exd5 exd5 4. Nf3 Nf6 5. Bd3 Bd6 6. O-O O-O 7. Bg5 Bg4 8.
>Nbd2 Nbd7 9. c3 h6 10. Bh4 c5 11. dxc5 Nxc5 12. Qc2 g5 13. Bg3 Bxg3 14. hxg3
>Re8 15. Nd4 Nxd3 16. Qxd3 Qb6 17. N2b3 a5 18. a4 Bd7 19. Ra3 Re5 20. Qd2 Rae8
>21. Nc1 Ne4 22. Qc2 Nc5 23. Nd3 Nxd3 24. Qxd3 Qxb2 25. Rb3 Qa2 26. Rxb7 Qxa4
>27. Qd2 R5e7 28. Rb6 Kg7 29. f4 Qc4 30. fxg5 h5 31. Rh6 Qc7 32. Qd3 Rh8 33. Qf3
>Qe5 34. Rf6 Rf8 35. Qxh5 Qe4 36. R1f5 Qb1+ 37. Kh2 Bxf5 38. Nxf5+ Qxf5 39. Qh6+
>Kg8 40. Rxf5 Re6 41. g6 Rxg6 42. Rg5 Rxg5 43. Qxg5+ Kh7 44. Qxd5 Kg6 45. Qxa5
>Rh8+ 46. Kg1 f6 47. g4 Rf8 48. Qf5+ Kg7 49. g5 fxg5 50. Qxg5+ Kh7 51. Qg4 Rg8
>52. c4 Rxg4 53. g3 Rxc4 54. Kg2 Re4 55. Kf3 Re6 56. Kg4 Kg6 57. Kf4 Re8 58. g4
>Kf6 59. g5+ Kg6 60. Kg4 Rf8 61. Kh4 Rf4+ 62. Kh3 Kxg5 63. Kg3 Rf8 64. Kh3 Kf4
>65. Kg2 Kg4 66. Kh2 Kf3 67. Kh1 Kf2 0-1
>
>51. Qg4 ... 52. ... Rxg4
>Seems Gromit was lucky :)

No, Gromit just had less bugs :-).  I have found another example of
the bug in the winboard-tournament.  That's game #443 against ANT.
There are probably others, less obvious.

I want to add that i like Gromit's playing style.  It always fights
for initiative and piece mobility.  Do you still plan to release it
in sources?

>>Dusan
>Frank



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