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# Think Like a Chess Engine

Aug 15, 2010, 8:05 AM 2

In Kotov's great book "Think Like a Grandmaster" he taught the average chess player the inner workings of how a chess master thinks about a position by creating a tree of candidates and then proceeding along the tree. While there is much to learn from Kotov's work, I have always been facinated how computers can evaluate positions and how their positional play is derived from these material evaluation algorithms. I believe that the way chess engines derive material evaluations might help the lower rated amateur improve their evaluation skills.

Below is a combination of the Crafty chess engine algorithms as well as Larry Kaufman's material evaluation processes which is used by the Rybka engine.

Pawns

Pawn = 1

isolated pawn penalty based on file:
a-pawn : -.12
b-pawn : -.14
c-pawn : -.16
d-pawn : -.20
e-pawn : -.20
f-pawn : -.16
g-pawn : -.14
h-pawn : -.12

Doubled pawn (and not also isolated) penalty of -.12 plus add isolated pawn penalty

Backward pawns -.06 penalty +.04 bonus for attack on backward pawn on semi-open file.

Pawn advance in center +.04 / rank increasing to about +.08 / rank in the endgame
Development

Rook pawn is worth 15% less than a regular pawn (.85 of a pawn) (L.Kaufman)

Knights

Knights = 3.25
Centralized knight: +.30
In outpost : +.08

Unpaired knight is worth approximately 3.14 pawns (worth less) (L.Kaufman)

Bishops

Bishops = 3.25
Bishop in endgame +.10
Corner bishop : 0.0
Center bishop: +.3
Attacking / good bishop: +.18
Attack against King: +.05

The Bishop Pair

Bishop pair: +.50  Bishop pair is worth .50 more if not pieces exist to exchange them (L.Kaufman)

Bishop pair is worth less than .50 a pawn when most or all of the pawns are on the board, and more than .50 pawns when half or more of the pawns are gone (L.Kaufman)

If you have the bishop pair, and your opponent’s single bishop is a bad bishop (hemmed in by his own pawns), you already have full compensation for 1 pawn (L.Kaufman)

Unpaired bishop is worth approximately 3.14 pawns (worth less) (L.Kaufman)

Rooks

Rooks = 5
Attacking on open-file: +.20
One semi-open file: +.10
On open-file: +.14

Rook and Bishop is better than the Rook and Knight. (L.Kaufman)

Queen

Queen = 9.75

Queen and Knight is slightly better than Queen and Bishop

King
Centralized in opening: -.24
Centralized in endgame: +.36
On open file in opening: -.23

Special Cases

Hanging pieces: -.10

Exchanges favor the side with a material advantage

Minor pieces lose their value as the endgame approaches

In endgames with no other piece the bishop is worth about 2.5 and the knight 2.25 with other pieces the minors are worth about 3.25

Rooks gain value as the endgame approaches

Note: I have modified the Crafty point values to reflect the Kaufman values.

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Resources

Evaluation of Material Imbalances in Chess

GNU Chess Positional Heuristics

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