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Subject: Re: Good, Bad and Active Bishop

Author: Scott Gasch

Date: 15:13:45 01/10/02

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On January 10, 2002 at 16:23:44, David Rasmussen wrote:

>What techniques do people use for assessing good, bad and active bishops? As I
>do it now, a good bishop is one with no central pawns on the same color, a bad
>bishop is one with at least one pawn on the same color, and an active bishop is
>one that isn't looking into a pawn when looking in the direction of the center.
>Right now, I don't consider whether the pawns in question are blocked or not,
>which is also important.

Bishops terms in my engine:

mobility: number of squares it can safely move to.
trapped: no mobility and under threat.
development: get it off the back rank in opening
enemy king tropism: the closer the better
outposted: no enemy pawns can advance and attack the bishop
fianchetto: bonus for defending king.  more bonus if the enemy has lost the
 bishop of the same color.
pointed near the enemy king: good to point at or near enemy king pos -- this
 term is scaled back the more pieces there are between us and the enemy king.
good / bad: based on the number and location of pawns on its color.  This also
 helps the engine prefer knights in totally blocked positions.
active bad: must be in an outpost (no enemy pawns can attack).  must be
 supported by 1 pawn (if the enemy has no knight / same color bishop) or 2
 pawns (if the enemy has a knight or same color bishop).  Must point near the
 enemy king and control a large number of squares in the enemy camp.
bonus for protecting a passed pawn.
bonus for protecting the queening square of a passed pawn.

That's about it.
Scott

>
>In general, I think evaluation terms are not discussed enough in the CCC. Search
>techniques, book techniques, move generation etc. is discussed, but what makes,
>say, Gambit Tiger such a strong engine, is the unique evaluation terms, I think.
>I know Christophe wont say anything about his evaluation terms, but everybody
>else should feel free to talk :)
>
>/David



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