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Stockfish - material balance/imbalance evaluation
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Sven Schüle



Joined: 15 May 2008
Posts: 2249
Location: Berlin, Germany
PostPost subject: Re: Stockfish - material balance/imbalance evaluation    Posted: Fri May 07, 2010 10:31 am Reply to topic Reply with quote
Sven Schüle wrote:
mcostalba wrote:
Ralph Stoesser wrote:
The bad bishop issue is not only a mobility issue, but a long term mobility issue.
In chess engines "long term" is called "search depth"
Ralph Stoesser wrote:
By evaluating only the bishop's mobility, the engine has no knowledge about how deep behind the search horizon the mobility issue would be valid.
Are you sure ?

When we talk of "horizon" we are talking of about 20 moves ahead and counting... Wink

For human chess players the existence of "bad" bishops vs. either "good" bishops or knights in the middlegame can be an important reason to decide about trading pieces and going into an endgame or not. This can really be a "long term" issue, especially if the pawn structure is quite stable due to blocked pawns. For an engine, even a 30-ply search in such middlegames may often end up in doing static evaluation of an early endgame position, where an estimate about "bad" bishops can be helpful.

Therefore I agree with Ralph stating that a bad bishop is not defined via current mobility only, i.e. the square color of pawns may be relevant, too, even if those pawns are currently not attacked or defended by the bishop.

Consider this example position:
[D]8/2kb1p2/5Pp1/1p4Pp/pP5P/P3K3/6B1/8 w - - 0 1[/D]
   ::    ::    ::    ::
::    BK BB :: BP ::    
   ::    ::    WP BP ::
:: BP ::    ::    WP BP
BP WP    ::    ::    WP
WP    ::    WK    ::    
   ::    ::    :: WB ::
::    ::    ::    ::    

Even a shallow (e.g. 12 ply) search finds that white can win easily, everyone can figure this out. But strong human chess players, and not only the strongest ones, "know" from looking at the position, or can visualize during analysis, that black has the bad bishop and will lose by some kind of zugzwang. So strong humans will evaluate this position as "won" without further search, as soon as they detect that the white king is active enough to reach the fourth rank and oppose the black king. (You may consider this to be like "search", of course ...)

Stockfish 1.7.1 analysis, for instance:
Code:
 12   +2.06   18747   0:00.08   Bd5 Be8 Kd4 Kd6 Ba2 Kc6 Ke5 Kc7 Kd5 Kd8 Kc5 Kd7 Kxb5 Kd6+ Kb6 Ke5 Bc4 Kf5

where a human analysis would probably include 6...Kc7 7.Bd5 (zugzwang) Kd8 8.Bc6 instead of 6...Kd7 7.Kxb5.

But there is no close relation to the current mobility of both bishops in this case. Black bishop has mobility to 7 squares, so who would call him "bad" based on only that? It is the fact that all black pawns are on the bishop's square color and blocked while he can't attack any single white pawn that makes him appear very bad.

Sven
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Subject Author Date/Time
Stockfish - material balance/imbalance evaluation Ralph Stoesser Wed May 05, 2010 4:39 pm
      Re: Stockfish - material balance/imbalance evaluation Marco Costalba Wed May 05, 2010 4:48 pm
            Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Wed May 05, 2010 5:37 pm
                  Re: Stockfish - material balance/imbalance evaluation Marco Costalba Wed May 05, 2010 5:47 pm
      Re: Stockfish - material balance/imbalance evaluation Jan Brouwer Wed May 05, 2010 5:49 pm
            Re: Stockfish - material balance/imbalance evaluation Eelco de Groot Wed May 05, 2010 7:25 pm
                  Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Wed May 05, 2010 8:02 pm
                        Re: Stockfish - material balance/imbalance evaluation Eelco de Groot Wed May 05, 2010 10:10 pm
                              Re: Stockfish - material balance/imbalance evaluation Milos Stanisavljevic Wed May 05, 2010 10:30 pm
                                    Re: Stockfish - material balance/imbalance evaluation Eelco de Groot Wed May 05, 2010 10:47 pm
                                    Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Wed May 05, 2010 11:27 pm
                                          Re: Stockfish - material balance/imbalance evaluation Eelco de Groot Thu May 06, 2010 1:23 am
                                                Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Thu May 06, 2010 9:07 am
                                                      Re: Stockfish - material balance/imbalance evaluation Sven Schüle Thu May 06, 2010 9:31 am
                                                            Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Thu May 06, 2010 9:52 am
                                                                  Re: Stockfish - material balance/imbalance evaluation Sven Schüle Thu May 06, 2010 10:48 am
                                                                        Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Thu May 06, 2010 12:08 pm
                                                                              Re: Stockfish - material balance/imbalance evaluation Tord Romstad Thu May 06, 2010 8:24 pm
                                                      Re: Stockfish - material balance/imbalance evaluation Eelco de Groot Thu May 06, 2010 1:19 pm
                                                Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Fri May 07, 2010 9:34 pm
                                                      Re: Stockfish - material balance/imbalance evaluation Marco Costalba Sat May 08, 2010 12:48 pm
                                                            Re: Stockfish - material balance/imbalance evaluation Eelco de Groot Sat May 08, 2010 1:47 pm
                                                            Re: Stockfish - material balance/imbalance evaluation Marcel van Kervinck Sat May 08, 2010 2:01 pm
                                          Re: Stockfish - material balance/imbalance evaluation Marco Costalba Thu May 06, 2010 11:40 am
                              Re: Stockfish - material balance/imbalance evaluation Eelco de Groot Wed May 05, 2010 10:42 pm
      Re: Stockfish - material balance/imbalance evaluation Joona Kiiski Wed May 05, 2010 7:54 pm
            Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Wed May 05, 2010 8:28 pm
            Re: Stockfish - material balance/imbalance evaluation Larry Kaufman Sun May 27, 2012 7:31 pm
      Re: Stockfish - material balance/imbalance evaluation Tord Romstad Thu May 06, 2010 8:16 pm
            Re: Stockfish - material balance/imbalance evaluation James Coit Thu May 06, 2010 10:13 pm
            Re: Stockfish - material balance/imbalance evaluation Vratko Polák Thu May 06, 2010 11:38 pm
            Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Fri May 07, 2010 12:15 am
                  Re: Stockfish - material balance/imbalance evaluation Marco Costalba Fri May 07, 2010 5:39 am
                        Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Fri May 07, 2010 8:09 am
                              Re: Stockfish - material balance/imbalance evaluation Marco Costalba Fri May 07, 2010 8:25 am
                                    Re: Stockfish - material balance/imbalance evaluation Sven Schüle Fri May 07, 2010 9:48 am
                                          Re: Stockfish - material balance/imbalance evaluation Sven Schüle Fri May 07, 2010 10:31 am
                                          Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Fri May 07, 2010 10:54 am
                                          Re: Stockfish - material balance/imbalance evaluation Miguel A. Ballicora Fri May 07, 2010 10:31 pm
                                                Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Sat May 08, 2010 1:33 pm
                                                      Re: Stockfish - material balance/imbalance evaluation Marco Costalba Sat May 08, 2010 2:29 pm
                                                            Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Sat May 08, 2010 4:24 pm
                                                                  Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Sat May 08, 2010 7:54 pm
                                                                        Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Sun May 09, 2010 3:19 pm
                                                                              Re: Stockfish - material balance/imbalance evaluation Marco Costalba Sun May 09, 2010 4:47 pm
                                                                                    Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Sun May 09, 2010 7:51 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Marco Costalba Sun May 09, 2010 10:47 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Sun May 09, 2010 11:22 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Marco Costalba Mon May 10, 2010 4:58 am
                                                                                          Re: Stockfish - material balance/imbalance evaluation Sven Schüle Mon May 10, 2010 7:39 am
                                                                                          Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Mon May 10, 2010 10:22 am
                                                                                          Re: Stockfish - material balance/imbalance evaluation Eelco de Groot Mon May 10, 2010 5:04 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Mon May 10, 2010 9:35 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Marco Costalba Tue May 11, 2010 11:19 am
                                                                                          Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Tue May 11, 2010 1:51 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Tue May 11, 2010 9:38 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Marco Costalba Wed May 12, 2010 5:05 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Robert Hyatt Wed May 12, 2010 6:14 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Marco Costalba Wed May 12, 2010 6:39 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Thu May 13, 2010 12:51 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Wed May 12, 2010 8:13 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Wed May 12, 2010 9:15 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Marco Costalba Wed May 12, 2010 9:34 pm
                                                                                          Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Wed May 12, 2010 10:02 pm
                                                            Re: Stockfish - material balance/imbalance evaluation Eelco de Groot Sat May 08, 2010 4:53 pm
                                                                  Re: Stockfish - material balance/imbalance evaluation Ralph Stoesser Sat May 08, 2010 7:03 pm
            Re: Stockfish - material balance/imbalance evaluation Vincent Diepeveen Wed Jul 28, 2010 6:10 pm
                  Re: Stockfish - material balance/imbalance evaluation Milos Stanisavljevic Wed Jul 28, 2010 6:24 pm
                        Re: Stockfish - material balance/imbalance evaluation grzegorzs Thu Aug 05, 2010 5:36 pm
                  Re: Stockfish - material balance/imbalance evaluation Dann Corbit Wed Jul 28, 2010 6:43 pm
                        Re: Stockfish - material balance/imbalance evaluation Vincent Diepeveen Wed Jul 28, 2010 7:43 pm
                              Re: Stockfish - material balance/imbalance evaluation Vincent Diepeveen Wed Jul 28, 2010 7:44 pm
                                    Re: Stockfish - material balance/imbalance evaluation Joona Kiiski Wed Jul 28, 2010 7:55 pm
                                          Re: Stockfish - material balance/imbalance evaluation Vincent Diepeveen Wed Jul 28, 2010 8:30 pm
                                                Re: Stockfish - material balance/imbalance evaluation Milos Stanisavljevic Wed Jul 28, 2010 9:30 pm
                                                      Re: Stockfish - material balance/imbalance evaluation Vincent Diepeveen Wed Jul 28, 2010 10:11 pm
                                                            Re: Stockfish - material balance/imbalance evaluation Milos Stanisavljevic Wed Jul 28, 2010 10:31 pm
                                                                  Re: Stockfish - material balance/imbalance evaluation Vincent Diepeveen Wed Jul 28, 2010 10:57 pm
                                                            Crazy talk Ben-Hur Carlos Langoni Wed Jul 28, 2010 11:07 pm
                                                                  Re: Crazy talk Vincent Diepeveen Wed Jul 28, 2010 11:36 pm
                                                Re: Stockfish - material balance/imbalance evaluation Ben Stoker Wed Jul 28, 2010 10:07 pm
                                                      Re: Stockfish - material balance/imbalance evaluation Vincent Diepeveen Sun Aug 08, 2010 1:54 pm
                              Re: Stockfish - material balance/imbalance evaluation Robert Hyatt Wed Jul 28, 2010 8:27 pm
                                    Re: Stockfish - material balance/imbalance evaluation Dann Corbit Wed Jul 28, 2010 9:30 pm
                              Re: Stockfish - material balance/imbalance evaluation Wylie Garvin Tue Aug 10, 2010 10:00 pm
      Re: Stockfish - material balance/imbalance evaluation Tu Ngoc Trung Sun May 27, 2012 2:22 am
            Re: Stockfish - material balance/imbalance evaluation Ferdinand Mosca Sun May 27, 2012 10:01 am
                  Re: Stockfish - material balance/imbalance evaluation Tu Ngoc Trung Mon May 28, 2012 3:19 am
            Re: Stockfish - material balance/imbalance evaluation Eelco de Groot Mon May 28, 2012 4:19 am
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