MadChess 2.0 Beta Build 037 (Futility Pruning)

I added futility pruning to MadChess 2.0 Beta. In the main search, for non-capture moves, if the static score plus the futility margin is less than alpha, the move is considered too weak and is skipped. In the quiescence search, for capture moves, if the static score plus the material value of the captured piece plus the futility margin is less than alpha, the move is considered too weak and is skipped. The futility margin depends on the distance to the horizon, and is subject to other constraints, illustrated in the code below.

To Horizon Futility Margin (centipawns)
<1 (Quiescence Search) 100
1 150
2 250
3 400
4 600
>4 Not Futile

This added 54 ELO to the playing strength of MadChess 2.0 Beta.

MadChess 2.0                   2004 :    800 (+322,=144,-334),  49.3 %

vs.                                 :  games (   +,   =,   -),   (%) :   Diff,  SD, CFS (%)
BikJump v2.01                       :    100 (  18,  18,  64),  27.0 :    -98,  12,    0.0
Matheus-2.3                         :    100 (  28,  17,  55),  36.5 :    -75,  11,    0.0
Monarch 1.7                         :    100 (  26,  16,  58),  34.0 :    -54,  13,    0.0
BigLion 2.23w                       :    100 (  45,  11,  44),  50.5 :    -17,  10,    5.6
Sharper 0.17                        :    100 (  50,  13,  37),  56.5 :     -1,  12,   46.4
Faile 1.4                           :    100 (  42,  32,  26),  58.0 :    +24,  10,   98.8
Jabba13032012                       :    100 (  54,  22,  24),  65.0 :    +58,  11,  100.0
Roce 0.0390                         :    100 (  59,  15,  26),  66.5 :   +123,  11,  100.0
Feature Category Date Build Number WAC1 ELO Rating2 Improvement
Futility Pruning Search 2014 Dec 29 37 256 2004 +54
Null Move
Quiescence Recaptures
Search 2014 Dec 28 35 242 1950 +46
King Safety Evaluation 2014 Dec 24 32 225 1904 +27
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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