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Subject: Re: Endgame position / running passed pawns

Author: blass uri

Date: 22:04:37 06/05/00

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On June 05, 2000 at 22:49:03, William Bryant 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:
>>
>>5k2/7K/6P1/1p3p2/1P5P/1Pb5/8/8 w
>>
>>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.
>>
>
>Screamer picks h5 on ply 5, with a positive score by ply 6.
>I have _very_ little endgame evaluation code so this is just searching.
>
>I like Bob's comment about being more concerned with how long it takes to find
>the move rather than how deep it takes to get a positive score.
>
>William
>wbryant@ix.netcom.com
>
>New Board Position
>5k2/7K/6P1/1p3p2/1P5P/1Pb5/8/8 w
>Move 1 W>>
>PLY       NODES     TIME    SCORE  PV
>__________________________________________________
> 5/00      1984     0.029   -0.76  Kh6 Bxb4 g7+ Kg8 h5 f4
> 5/01      2956     0.085      ++  h5
> 5/01      3483     0.116   -0.13  h5 f4 h6 Ke7 g7
> 6/00      4793     0.159      ++  h5
> 6/00      6586     0.208   +0.65  h5 Ke7 g7 Bxg7 Kxg7 f4 h6
> 7/00      9517     0.277   +1.00  h5 Bg7 h6 Bxh6 Kxh6 f4 g7+ Kf7 Kg5 Kxg7 Kxf4
> 8/00     13018     0.351   +1.08  h5 Bg7 h6 Bxh6 Kxh6 f4 g7+ Kg8 Kg6 f3

This line proves that Screamer has a positive score for the wrong reason.
This line is losing for white because the f3 pawn cannot be stopped but
screamer does not know to evaluate unstoppable passed pawns.

Uri



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