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Subject: Re: an evaluation problem of chess programs

Author: Robert Hyatt

Date: 11:15:54 10/01/98

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On October 01, 1998 at 11:40:46, blass uri wrote:

>
>On October 01, 1998 at 08:21:43, Robert Hyatt wrote:
>
>>On October 01, 1998 at 01:11:12, blass uri wrote:
>>
>>>
>>>
>>>
>>>8/1r5p/6p1/8/P2k4/K6P/1R4P1/8 black to move
>>>
>>>Many programs are playing Rxb2 because they computes that white is losing its
>>>pawn in the pawn endgame and do not understand that after Rxb2 Kxb2 Kc4 Kc2 Kb4
>>>Kd3 Kxa4 white is winning.
>>>
>>>Rxb2 is not the first move they want to play because they need time to see that
>>>black wins a pawn by this stupid mistake after Rxb2 Kxb2 Kc4 Ka3
>>>
>>>Is there a program that understand by static evaluation that white is winning
>>>with the king at d3?(static evaluation at least 1.5 pawn advantage for white)
>>>
>>>Uri
>>
>>I get this:
>>
>>       +---+---+---+---+---+---+---+---+
>>    8  |   |   |   |   |   |   |   |   |
>>       +---+---+---+---+---+---+---+---+
>>    7  |   | *R|   |   |   |   |   | *P|
>>       +---+---+---+---+---+---+---+---+
>>    6  |   |   |   |   |   |   | *P|   |
>>       +---+---+---+---+---+---+---+---+
>>    5  |   |   |   |   |   |   |   |   |
>>       +---+---+---+---+---+---+---+---+
>>    4  | P |   |   | *K|   |   |   |   |
>>       +---+---+---+---+---+---+---+---+
>>    3  | K |   |   |   |   |   |   | P |
>>       +---+---+---+---+---+---+---+---+
>>    2  |   | R |   |   |   |   | P |   |
>>       +---+---+---+---+---+---+---+---+
>>    1  |   |   |   |   |   |   |   |   |
>>       +---+---+---+---+---+---+---+---+
>>         a   b   c   d   e   f   g   h
>>
>>Black(1): sc
>>end-game phase
>>              clearing hash tables
>>note: scores are for the white side
>>material evaluation.................   1.00
>>development.........................   0.00
>>pawn evaluation.....................   0.12
>>passed pawn evaluation..............   0.24
>>passed pawn race evaluation.........   0.00
>>interactive piece evaluation........  -0.23
>>total evaluation....................   1.13
>
>I did not ask about the static evaluation of the originial position but about
>the static evaluation of the position after the line Rxb2 Kxb2 Kc4 Kc2 Kb4 kd3
>kxa4
>
>
>>
>>
>>
>>when I do a search, I never get "rxb2" as reasonable:
>
>programs get Rxb2 as reasonable because of the following line
>Rxb2 Kxb2 Kc4 Ka3 g5 g3 h5 g4 h4 Kb2 Kb4 kc2 kxa4
>they need time to find this line(more than 1 or 2 seconds).
>white also  can win this pawn ending but programs do not understand this.
>
>Uri


first, I let crafty search for > 6 minutes.  *no* Rxb2.

Next, I tried your variation above where you say "programs do not under stand
this".  Would you call this "understanding that white can win that ending"???

              time surplus   0.00  time limit 1666:39 (1666:39)
              depth   time  score   variation (1)
               10     0.30  Mat19   8. Kd3 Kb5 9. Ke4 Kc4 10. Kf5 Kd3 11.
                                    Kxg5 Kd4 12. Kxh4 <EGTB>
               10->   0.31  Mat19   8. Kd3 Kb5 9. Ke4 Kc4 10. Kf5 Kd3 11.
                                    Kxg5 Kd4 12. Kxh4 <EGTB>
              time=0.32  cpu=18%  mat=0  n=7341  fh=97%  nps=22940


IE *some* programs can figure that out quite easily, and not enter a line
that is dead lost.  This is probably why I don't get Rxb2 *ever*.  It
"knows" better...



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