Author: Steffen Jakob
Date: 06:18:29 06/05/00
Go up one level in this thread
Hi Bob!
On June 05, 2000 at 09:09:51, Robert Hyatt wrote:
>On June 05, 2000 at 08:22:44, Steffen Jakob wrote:
>
>>Hi!
>>
>>This is a position from an interesting standard game MissSilicon - Hossa, played
>>today at ICC:
>>
>>[D]5k2/7K/6P1/1p3p2/1P5P/1Pb5/8/8 w
>
>
>
>I think there are times where you have to depend on your search. Normally
>this is won by black, because black has a bishop to stop white's pawns. I
>suspect that if you try to write special-purpose code to catch this, it will
>end up being wrong more than it is right. This is a precise tempo-counting
>issue that just barely lets the 'loser' win.
>
>I'd likely just take the loss and run. It takes Crafty 9 plies (0 seconds
>of course) to see that the bishop is not winning. I don't see an obvious
>evaluation trick to make this show up faster...
The problem here is not only speed but mainly depth! You are right that it might
be difficult to catch this faster by eval than by evaluation. But what if this
position appears deep in the search and you have to trade some pieces to reach
this position (so the actual board position might be complex)? Then you simply
dont search deep enough to see that white is winning. The board position might
be complex enought so that you stop after lets say 7 plies of the line above and
evaluate that as good for black. If you catch it by evaluation you wont make the
bad trades.
Best wishes,
Steffen.
>>White is obviously winning. The static evaluation of this position of my program
>>is totally wrong because Hossa thinks that the pawn f5 is running. Even after
>>some improvements Hossa needs 8 plies to see a positive score!
>>
>> depth value time nodes pv
>> 1 -6.07 0.00 3 1.g7 c3xg7
>> 2/1 -3.62 0.00 6 1.h5 c3xb4
>> <1> -3.62 0.00 7 1.h5 c3xb4
>> 2 -3.62 0.00 24 1.h5 c3xb4
>> <2> -3.62 0.00 40 1.h5 c3xb4
>>! 3 -1.77 0.01 544 1.h5 f4 2.h6 c3xb4
>>! <3> -1.77 0.01 551 1.h5 f4 2.h6 c3xb4
>> 4 -1.87 0.03 1214 1.h5 f4 2.h6 f8e8 3.h7g8 c3xb4
>> <4> -1.87 0.03 1245 1.h5 f4 2.h6 f8e8 3.h7g8 c3xb4
>> 5 -1.67 0.05 2303 1.h5 c3g7 2.h6 g7xh6 3.h7xh6
>> <5> -1.67 0.05 2375 1.h5 c3g7 2.h6 g7xh6 3.h7xh6
>> 6 -1.81 0.09 4316 1.h5 c3g7 2.h6 g7xh6 3.h7xh6 f4
>> <6> -1.81 0.09 4691 1.h5 c3g7 2.h6 g7xh6 3.h7xh6 f4
>> 7 -1.81 0.20 9875 1.h5 c3g7 2.h6 g7xh6 3.h7xh6 f4
>> <7> -1.81 0.21 10423 1.h5 c3g7 2.h6 g7xh6 3.h7xh6 f4
>>! 8 0.76 0.61 31734 1.h5 c3g7 2.h6 g7xh6 3.h7xh6 f8g8
>> 4.h6g5
>>! <8> 0.76 0.61 31775 1.h5 c3g7 2.h6 g7xh6 3.h7xh6 f8g8
>> 4.h6g5
>>! 9 2.19 0.85 47414 1.h5 c3g7 2.h6 g7xh6 3.h7xh6 f8g8
>> 4.h6g5 g8f8 5.g5xf5
>>! <9> 2.19 0.85 47456 1.h5 c3g7 2.h6 g7xh6 3.h7xh6 f8g8
>> 4.h6g5 g8f8 5.g5xf5
>>
>>
>>Does your engine perform better here? Any ideas how to handle such positions?
>>
>>Best wishes,
>>Steffen.
>>
>>P.S.: Here is the complete game score:
>>
>>[Event "ICC 30 20"]
>>[Site "Internet Chess Club"]
>>[Date "2000.06.05"]
>>[Round "-"]
>>[White "MissSilicon"]
>>[Black "Hossa"]
>>[Result "1-0"]
>>[ICCResult "Black checkmated"]
>>[WhiteElo "2437"]
>>[BlackElo "2358"]
>>[Opening "Bird's opening"]
>>[ECO "A03"]
>>[NIC "VO.07"]
>>[Time "01:51:53"]
>>[TimeControl "1800+20"]
>>
>>1. f4 d5 2. Nf3 Nf6 3. b3 d4 4. c3 c5 5. Qc2 Nc6 6. e3 Bd7 7. cxd4 cxd4 8.
>>Nxd4 Nxd4 9. exd4 Bc6 10. Bb2 Rc8 11. Nc3 Qxd4 12. Nb5 Qb6 13. Bd4 Qd8 14.
>>Qb2 Be4 15. Nxa7 Rc2 16. Bb5+ Nd7 17. Qb1 e5 18. O-O exd4 19. Re1 Qe7 20.
>>Nc8 Qc5 21. Rxe4+ Kd8 22. b4 Qxc8 23. Rxd4 Rc7 24. Qb3 Be7 25. Re1 Bf6 26.
>>Rde4 Rc1 27. Qxf7 Rxe1+ 28. Rxe1 Qc7 29. Kh1 Kc8 30. Bxd7+ Qxd7 31. Rc1+ Kd8
>>32. Qh5 b6 33. d3 Re8 34. h3 Bb2 35. Rc4 Qxd3 36. Qb5 Qd6 37. Qf5 Qd7 38.
>>Qxh7 Re1+ 39. Kh2 Bf6 40. Qc2 Bd4 41. Kg3 b5 42. Rc6 Re6 43. Rxe6 Qxe6 44.
>>Kf3 Qe3+ 45. Kg4 Qc3 46. Qb1 Qd2 47. g3 Qe2+ 48. Kf5 Qf3 49. Qb3 Qxb3 50.
>>axb3 Ke7 51. Kg6 Kf8 52. g4 Bf2 53. f5 Bh4 54. g5 Ke7 55. Kh5 Bg3 56. Kg6
>>Be5 57. h4 Bc3 58. Kh7 Kf8 59. f6 gxf6 60. g6 f5 61. h5 Bg7 62. h6 Bc3 63.
>>g7+ Kf7 64. g8=Q+ Ke7 65. Kg6 Bxb4 66. Qg7+ Ke6 67. h7 Be7 68. h8=Q Kd7 69.
>>Qd4+ Kc7 70. Qc3+ Kb6 71. Qb8+ Ka6 72. Qa1+ Ba3 73. Qxa3# {Black checkmated}
>>1-0
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.