Author: Robert Hyatt
Date: 08:43:22 10/03/05
Go up one level in this thread
On October 02, 2005 at 13:49:37, Will Singleton wrote:
>White wins easily by promoting and exchanging queens, but most comps can't see
>it.
>
>[d]8/5p1P/8/8/6K1/5P2/1k6/q7 w - -
>
>Amateur failed to exchange queens, and drew the game. I'm not quite sure why,
>seems like a simple search should be enough to handle this. Oddly, if the
>exchange is forced, the win is seen immediately. This happens with other progs
>as well. I thought I had taken steps to eliminate root-position dependencies in
>the search, but maybe something else is happening.
>
>Will
Here is what you need:
Your program probably understands that if you remove the black queen, white is
winning because of the "outside passed pawn"??? (ignore the fact that the pawn
promotes instantly for now). If so, you need one more critical piece of
knowledge.
Your program needsd to realize that if things are not obvious, no pawn to
promote, no distant passer on the board, but its king is closer to the remaining
pawns than the enemy king, the game is _still_ won.
Set up a position like white/black pawns locked up at a4/a5, white passer at h2,
both kings near the center of the board. The easiest way to win is to push the
h-pawn. Black has to go over and stop it, and once it is gone, white is too
close to the remaining black a-pawn and the game is over.
If you don't catch this case, you will play for a distant passer, but then
refuse to give it up, and once your king gets to the distant passer to defend
it, you can't force the promotion, and when you wait too long, as your king
finally gives up the passer, black eats it and then follows you across the board
and hems in your king on the a-file or else black gets to the a-file and the
game is a draw. But if you just push and get the black king too far away, you
win easily...
Crafty plays this move instantly with no endgame tables of any kind, and shows a
big +score for white immediately, due to the above...
>
>
>[Event "Computer chess game"]
>[Site "P4-2800GHZ"]
>[Date "2005.10.01"]
>[Round "1"]
>[White "Amateur 2.86"]
>[Black "fruit 2.2"]
>[Result "1/2-1/2"]
>[TimeControl "300+3"]
>
>1. Nf3 Nf6 2. d4 e6 3. c4 b6 4. g3 Ba6 5. b3 Bb7 6. Bg2 Bb4+ 7. Bd2 a5 8.
>O-O O-O 9. Nc3 Re8 10. a3 Bxc3 11. Bxc3 d6 12. Qd3 Nbd7 13. Qe3 Ra7 14.
>Rad1 h6 15. Rfe1 Qe7 16. Bb2 Be4 17. Nh4 Bxg2 18. Nxg2 e5 19. dxe5 dxe5 20.
>Rd2 Nc5 21. Nh4 Nce4 22. Rdd1 Ng5 23. f3 a4 24. b4 Qe6 25. Qd3 c5 26. bxc5
>Rc7 27. Qd6 Rxc5 28. Qxe6 Rxe6 29. Rd8+ Re8 30. Red1 Rxd8 31. Rxd8+ Kh7 32.
>Rd6 b5 33. cxb5 Rxb5 34. Rd2 Ne6 35. Nf5 Rc5 36. Nd6 Kg8 37. Kf2 g6 38. h3
>Ng5 39. Kg2 Kf8 40. h4 Ne6 41. Nb7 Rb5 42. Nd6 Rc5 43. Kh3 h5 44. Nb7 Rb5
>45. Nd6 Rc5 46. e4 Ne8 47. Nxe8 Kxe8 48. Rd5 Rxd5 49. exd5 Nc7 50. Bxe5 Kd7
>51. g4 Nb5 52. Bb2 Kd6 53. gxh5 gxh5 54. Kg3 Kxd5 55. Kf4 Kc4 56. Kg5 Kb3
>57. Bh8 Nxa3 58. Kxh5 Nc4 59. Kg4 a3 60. h5 Nb2 61. h6 a2 62. Bxb2 Kxb2 63.
>h7 a1=Q 64. h8=Q+ Ka2 65. Qa8+ Kb2 66. Qh8+ Ka2 67. Qa8+ Kb2 68. Qb7+ Kc3
>69. Qc7+ Kd2 70. Qxf7 Qg1+ 71. Kf5 Qc5+ 72. Kf4 Qe3+ 73. Kg4 Qg1+ 74. Kf5
>Qc5+ 75. Kg6 Qd6+ 76. Kh5 Qc5+ 77. Kg6 Qd6+ 78. Kh5 Qc5+ 79. Kh6 Qd6+ 80.
>Kh7 Ke3 81. Qb3+ Qd3+ 82. Qxd3+ Kxd3 83. Kh6 Ke3 84. Kg5 Kxf3
>{Draw by insufficient material} 1/2-1/2
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