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Subject: Re: King and pawn game tuner for your program

Author: John Merlino

Date: 14:17:04 06/27/02

Go up one level in this thread


On June 27, 2002 at 15:08:49, Andrew Dados wrote:

>On June 27, 2002 at 14:53:55, John Merlino wrote:
>
>>On June 27, 2002 at 13:38:32, Ferdinand S. Mosca wrote:
>>
>>>
>>>The king and pawn game is a very interesting exercise to program, is it
>>>difficult to perfect this ending?.
>>>
>>>How long will it take your favorite programs to see that 36. h5 is good for
>>>black.
>>>[D]8/k6p/8/2P2p2/2P1p3/7K/1P3P2/8 b - - 0 35
>>>sample program analysis on Athlon xp 1600+, 64MB hash
>>>Analysis by Gromit 3.8.2:
>>>
>>>36...h5 37.Kg3 Kb7 38.b3 Kc7 39.b4 Kc6 40.f4 Kc7 41.b5 Kb7 42.c6+ Kb6 43.c5+ Kc7
>>>44.Kh3 e3 45.Kg3 h4+ 46.Kg2 h3+ 47.Kf3
>>>  ±  (1.09)   Depth: 18   00:10:55
>>>36...h5
>>>  ±  (1.09)   Depth: 19   00:10:55
>>>36...h5
>>>  ±  (1.09)   Depth: 19   00:11:09
>>>
>>>more than 11 min, and yet the score still favors white.
>>>
>>>
>>>Analysis by Green Light Chess 2.18:
>>>
>>>36...h5 37.Kg3 Kb7 38.b4 Kc6 39.f4 Kc7 40.b5 Kd7 41.c6+ Kd6 42.Kf2 h4 43.Kg2 e3
>>>44.Kf3 h3 45.Kxe3 h2 46.c5+ Kxc5 47.c7 Kxb5 48.c8Q h1Q 49.Qxf5+
>>>  ±  (1.27)   Depth: 19   00:03:16  154355kN
>>>36...h5 37.Kg3 Kb7 38.b4 Kc6 39.f4 Kc7 40.b5 Kd7 41.c6+ Kd6 42.Kf2 h4 43.Kg2 e3
>>>44.Kf3 h3 45.Kxe3 h2 46.c5+ Kxc5 47.c7 Kxb5 48.c8Q h1Q 49.Qxf5+
>>>  ±  (1.27)   Depth: 19   00:03:17  155502kN
>>>
>>>still favors white.
>>>
>>>Regards,
>>>Dinan
>>
>>Chessmaster 9000 chooses h5 after three seconds, but still believes White is
>>winning after several minutes:
>>
>>Time	Depth	Score	Positions	Moves
>>0:00	2/6	2.17	2478		1...Kb7 2.b4 Kc6 3.Kh4 f4 4.Kg4
>>0:00	3/7	3.10	6394		1...Kb7 2.Kg3 Kc6 3.b4 Kd7 4.Kf4
>>					Ke6 5.b5
>>0:00	4/8	2.99	13077		1...Kb7 2.Kg3 Kc6 3.b4 Kd7 4.Kf4
>>					Ke6 5.b5 h5
>>0:00	5/9	3.19	19013		1...Kb7 2.Kg3 Kc6 3.b4 Kd7 4.b5
>>					Ke6 5.c6 Kd6 6.Kf4
>>0:00	6/10	2.14	43284		1...Kb7 2.b4 h5 3.b5 f4 4.c6+ Kc7
>>					5.Kg2 e3 6.Kf3 exf2 7.Kxf2 h4 8.c5
>>0:01	7/11	2.22	72473		1...Kb7 2.Kh4 Kc6 3.Kg5 Kxc5 4.b3
>>					f4 5.Kxf4 Kd4 6.c5 Kxc5 7.Kxe4
>>0:01	8/12	2.89	133419		1...Kb7 2.Kh4 f4 3.Kg4 e3 4.fxe3
>>					fxe3 5.Kf3 h5 6.Kxe3 h4 7.b4 h3
>>0:03	8/12	1.71	316053		1...h5 2.Kg3 Kb7 3.b4 Kc6 4.f4
>>					exf3ep 5.Kxf3 h4 6.Kf2 f4 7.Kg2
>>0:05	9/13	1.91	505001		1...h5 2.Kg3 Kb7 3.b4 Kc6 4.f4
>>					exf3ep 5.Kxf3 h4 6.Kf4 Kc7 7.b5 h3
>>0:14	10/14	1.87	1210094		1...h5 2.Kg3 Kb7 3.b4 Kc6 4.f4
>>					exf3ep 5.Kxf3 h4 6.Kf4 Kc7 7.b5
>>					h3 8.b6+ Kb7
>>0:30	11/15	2.19	2537703		1...h5 2.Kg3 Kb7 3.b4 Kc6 4.f4
>>					exf3ep 5.Kxf3 h4 6.Kf4 Kc7 7.b5
>>					Kb7 8.c6+ Kc7 9.c5 h3
>>1:37	12/16	1.94	7960434		1...h5 2.Kg3 Kb7 3.b4 Kc6 4.f4
>>					Kc7 5.b5 Kb7 6.c6+ Kb6 7.Kg2 h4
>>					8.Kf2 h3 9.Kg3 e3
>>4:14	13/17	1.93	20726457	1...h5 2.Kg3 Kb7 3.b4 Kc6 4.f4
>>					Kc7 5.b5 Kb7 6.c6+ Kb6 7.Kf2 h4
>>					8.c5+ Kc7 9.Kg2 e3 10.Kf3 h3
>>15:01	14/18	1.61	71024288	1...h5 2.Kg3 Kb7 3.b4 Kc6 4.f4
>>					Kc7 5.b5 Kb7 6.c6+ Kb6 7.Kh4 Kc7
>>					8.Kh3 e3 9.Kg2 h4 10.Kf1 h3 11.c5
>>
>>How can Black possibly win (or even draw) this game?
>>
>>jm
>
>In your last mainline cm gets into this position after 7. Kh4:
>[D]8/8/1kP5/1P3p1p/2P1pP1K/8/8/8 b - -
>
>now 7... e3 seems to win quite simply for black.

And that's why I'm not a very good chess player. I have discovered that CM9000
would have seen the win for Black if I had let the search go another ply or two.

Thanks for the lesson,

jm



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