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Improving evaluation of passed pawns
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Ben-Hur Carlos Langoni



Joined: 16 Oct 2008
Posts: 482
Location: Milky Way

PostPost subject: Improving evaluation of passed pawns    Posted: Sat Jan 22, 2011 6:06 pm Reply to topic Reply with quote

Is there any engine that evaluates correctly the position bellow?

[D] 8/p1p5/6pp/PPP2k2/8/4PK2/8/8 w - - 0 43
   ::    ::    ::    ::
BP    BP    ::    ::    
   ::    ::    :: BP BP
WP WP WP    :: BK ::    
   ::    ::    ::    ::
::    ::    WP WK ::    
   ::    ::    ::    ::
::    ::    ::    ::    


Stockfish gives me the static score -24

My engine' s static evaluation is -61

In my case the wrong evaluation is due to the bigger bonuses for the connected passers, but a human can instantly see it is a winning position for white.

This specific position is an easy win which the static eval can be fixed to work correctly, as we have only pawns left in the board and because the opponent king is far from the promotion line of the candidate passed pawn. Although if there is left some minor piece from the opposite side things become more difficult to evaluate it statically.

The next given position my engine reasonably evaluates as 11:

[D] 8/p1p2p2/6pp/PPP2k2/8/4PKP1/8/8 w - - 0 43
   ::    ::    ::    ::
BP    BP    :: BP ::    
   ::    ::    :: BP BP
WP WP WP    :: BK ::    
   ::    ::    ::    ::
::    ::    WP WK WP    
   ::    ::    ::    ::
::    ::    ::    ::    


Stockfish gives the same score for this one: -24.

I wonder if there is a better for evaluating statically such positions. I think it might not increase significantly the size of the code and may be worth a few Elo points.

One quick & dirty way of fixing that would be giving bigger bonuses for candidate passers when there is only pawns left in the board and the opposite king is away from the promotion line.

Bellow, another position which is evaluated incorrectly:

[D] 8/p1p2p2/6p1/PPP2k1p/K2P4/4P3/8/8 w - - 0 43
   ::    ::    ::    ::
BP    BP    :: BP ::    
   ::    ::    :: BP ::
WP WP WP    :: BK :: BP
WK ::    WP    ::    ::
::    ::    WP    ::    
   ::    ::    ::    ::
::    ::    ::    ::    


Stockfish static score: -80
In my case my engine evaluates this position as -1400 because of the many unstoppable pawns in the black side. ( It is such a huge bonus... Shocked )

Any thoughts?

Regards,
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Ben-Hur Carlos Langoni Junior
http://sourceforge.net/projects/redqueenchess/
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Subject Author Date/Time
Improving evaluation of passed pawns Ben-Hur Carlos Langoni Sat Jan 22, 2011 6:06 pm
      Re: Improving evaluation of passed pawns Karlo Bala Jr. Sat Jan 22, 2011 7:57 pm
            Re: Improving evaluation of passed pawns Ben-Hur Carlos Langoni Sat Jan 22, 2011 8:47 pm
                  Re: Improving evaluation of passed pawns Karlo Bala Jr. Sun Jan 23, 2011 1:23 am
                        Re: Improving evaluation of passed pawns Gerd Isenberg Sun Jan 23, 2011 9:51 am
                              Re: Improving evaluation of passed pawns Ben-Hur Carlos Langoni Sun Jan 23, 2011 10:35 am
                        Re: Improving evaluation of passed pawns Ben-Hur Carlos Langoni Sun Jan 23, 2011 9:55 am
                        Re: Improving evaluation of passed pawns Joona Kiiski Sun Jan 30, 2011 12:34 pm
      Re: Improving evaluation of passed pawns Ferdinand Mosca Sat Jan 22, 2011 8:06 pm
            Re: Improving evaluation of passed pawns Ben-Hur Carlos Langoni Sat Jan 22, 2011 9:24 pm
                  Re: Improving evaluation of passed pawns Ferdinand Mosca Sun Jan 23, 2011 2:49 am
                        Re: Improving evaluation of passed pawns Marc Halstern Sun Jan 23, 2011 3:50 am
                              Re: Improving evaluation of passed pawns Ben-Hur Carlos Langoni Sun Jan 23, 2011 8:57 am
                        Re: Improving evaluation of passed pawns Ben-Hur Carlos Langoni Sun Jan 23, 2011 9:30 am
      Re: Improving evaluation of passed pawns Jacob BÝrs Lind Tue Jan 25, 2011 10:18 pm
            Re: Improving evaluation of passed pawns Dann Corbit Tue Jan 25, 2011 11:07 pm
                  Re: Improving evaluation of passed pawns Tano-Urayoan Russi Roman Thu Feb 03, 2011 5:10 am
                        Re: Improving evaluation of passed pawns Dann Corbit Thu Feb 03, 2011 7:33 pm
                              Re: Improving evaluation of passed pawns Tano-Urayoan Russi Roman Fri Feb 04, 2011 1:37 am
                                    Re: Improving evaluation of passed pawns Dann Corbit Fri Feb 04, 2011 3:10 am
                                          Re: Improving evaluation of passed pawns Don Dailey Fri Feb 04, 2011 5:01 pm
                                          Re: Improving evaluation of passed pawns Tano-Urayoan Russi Roman Sat Feb 05, 2011 4:16 am
                                                Re: Improving evaluation of passed pawns Dann Corbit Sat Feb 05, 2011 5:28 am
                        Re: Improving evaluation of passed pawns Jacob BÝrs Lind Fri Feb 04, 2011 3:04 pm
      Re: Improving evaluation of passed pawns Don Dailey Sat Jan 29, 2011 11:17 pm
      Re: Improving evaluation of passed pawns Robert Hyatt Sun Jan 30, 2011 2:26 am
            Re: Improving evaluation of passed pawns Gerd Isenberg Sun Jan 30, 2011 9:27 am
                  Re: Improving evaluation of passed pawns Robert Hyatt Sun Jan 30, 2011 2:18 pm
            Re: Improving evaluation of passed pawns Ben-Hur Carlos Langoni Sun Jan 30, 2011 10:43 am
                  Re: Improving evaluation of passed pawns Robert Hyatt Sun Jan 30, 2011 2:21 pm
                  Re: Improving evaluation of passed pawns Don Dailey Sun Jan 30, 2011 6:35 pm
                        Re: Improving evaluation of passed pawns Gerd Isenberg Sun Jan 30, 2011 7:23 pm
                              Re: Improving evaluation of passed pawns Don Dailey Sun Jan 30, 2011 8:08 pm
                                    Re: Improving evaluation of passed pawns Ben-Hur Carlos Langoni Sun Jan 30, 2011 8:26 pm
                                          Re: Improving evaluation of passed pawns Ben-Hur Carlos Langoni Sun Jan 30, 2011 8:43 pm
                                                Re: Improving evaluation of passed pawns Ben-Hur Carlos Langoni Sun Jan 30, 2011 8:58 pm
                                                      Re: Improving evaluation of passed pawns Robert Houdart Sun Jan 30, 2011 9:27 pm
                                                            Re: Improving evaluation of passed pawns Ben-Hur Carlos Langoni Sun Jan 30, 2011 9:47 pm
                                                                  Re: Improving evaluation of passed pawns Robert Houdart Sun Jan 30, 2011 10:11 pm
      Re: Improving evaluation of passed pawns Tano-Urayoan Russi Roman Thu Feb 03, 2011 4:26 am
            Re: Improving evaluation of passed pawns Robert Hyatt Thu Feb 03, 2011 6:10 am
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