MadChess 2.0 Beta Build 029 (Piece Mobility)

I added piece mobility evaluation to MadChess 2.0 Beta. The candidate moves of each piece are counted (move legality is not tested) and a non-linear bonus is assigned. Pieces with few moves are penalized. Pieces with many moves are awarded. Assigning a non-linear bonus encourages MadChess to develop all of its pieces, as opposed to maximizing the candidate moves of a few pieces. For example, more centipawns are awarded for increasing the candidate moves of a knight from three to six moves than for increasing the candidate moves of a queen from 14 to 20.

This added 64 ELO to the playing strength of MadChess 2.0 Beta.

MadChess 2.0                   1877 :    800 (+208,=134,-458),  34.4 %

vs.                                 :  games (   +,   =,   -),   (%) :   Diff,  SD, CFS (%)
BikJump v2.01                       :    100 (  13,  17,  70),  21.5 :   -204,  12,    0.0
Matheus-2.3                         :    100 (  12,  22,  66),  23.0 :   -186,  13,    0.0
Monarch 1.7                         :    100 (  31,  10,  59),  36.0 :   -151,  13,    0.0
BigLion 2.23w                       :    100 (  30,  15,  55),  37.5 :   -127,  12,    0.0
Faile 1.4                           :    100 (  17,  29,  54),  31.5 :   -123,  11,    0.0
Sharper 0.17                        :    100 (  43,   9,  48),  47.5 :   -104,  12,    0.0
Jabba13032012                       :    100 (  35,  11,  54),  40.5 :    -55,  11,    0.0
Roce 0.0390                         :    100 (  27,  21,  52),  37.5 :    +16,  10,   94.1
Feature Category Date Build Number WAC1 ELO Rating2 Improvement
Piece Mobility Evaluation 2014 Dec 16 29 225 1877 +64
Draw By Repetition Bug Evaluation 2014 Dec 10 27 225 1813 +47
Passed Pawns Evaluation 2014 Dec 09 26 225 1766 +72
Time Management Search 2014 Dec 08 25 231 1694 +24
Delay Move Generation
Aspiration Window Bug
Search 2014 Dec 02 23 231 1670 +44
MVV / LVA Move Order
Draw By Insufficient Material
Move List Overflow Bug
Search 2014 Dec 01 22 235 1626 +30
Tapered Evaluation
MG and EG Piece Location
Evaluation 2014 Nov 29 21 234 1596 +107
Alpha / Beta Negamax
Aspiration Windows
Quiescence, Hash
Material, Piece Squares
Baseline 2014 Nov 25 20 236 1489
  1. Win At Chess position test, 3 seconds per position
  2. Bullet chess, 2 min / game + 1 sec / move
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2 Comments

  1. Thanks a lot for your post. I used your idea of nonlinear mobility in my evaluation in my own engine and it scored 45 Elo!

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