MadChess 2.0 Beta Build 123 (Rook And Queen On 7th Rank)

I added rook and queen on 7th rank evaluation to MadChess 2.0 Beta. The code awards a bonus for a rook or queen on the 7th rank if the enemy king is on the 8th rank (its 1st rank).

Also, I removed late move pruning. (When I implemented late move pruning in build 44 it added 39 ELO to the playing strength of MadChess 2.0 Beta.) I replaced it with more aggressive null and late move reductions, and more aggressive futility pruning, but found it decreased the playing strength. Next, I restored late move pruning and left in the aggressive reductions. I found the strength increased, but not quite back to where it had been. I discovered a non-linear relationship between these search techniques. The combined strength of null move reductions, LMR, LMP, and futility pruning is not additive. I experimented with various parameter configurations before deciding to abandon LMP. It took 300 hours of testing to confirm the revised search was equivalently strong to the search with LMP.

This added 20 ELO to the playing strength of MadChess 2.0 Beta.

MadChess 2.0             2306.9 :   1600 (+835,=299,-466),  61.5 %

vs.                             :  games (   +,   =,   -),   (%) :    Diff,    SD, CFS (%)
Glass 1.6                       :    100 (  22,  24,  54),  34.0 :  -140.1,  15.0,    0.0
RomiChess P3L                   :    100 (  20,  20,  60),  30.0 :  -133.7,  16.2,    0.0
OliThink 5.3.2                  :    100 (  23,  20,  57),  33.0 :  -109.7,  15.5,    0.0
Myrddin 0.87                    :    100 (  31,  21,  48),  41.5 :   -75.0,  17.3,    0.0
Sungorus 1.4                    :    100 (  49,  15,  36),  56.5 :    -3.1,   8.2,   35.2
FireFly v2.6.0                  :    100 (  47,  31,  22),  62.5 :   +89.0,  10.0,  100.0
ZCT 0.3.2450                    :    100 (  42,  28,  30),  56.0 :   +94.7,  10.8,  100.0
Beowulf 2.4                     :    100 (  59,  19,  22),  68.5 :   +97.1,  13.0,  100.0
Jazz v444                       :    100 (  60,  17,  23),  68.5 :  +108.9,  10.0,  100.0
Brainless 1.0                   :    100 (  57,  17,  26),  65.5 :  +148.2,  17.8,  100.0
Wing 2.0                        :    100 (  61,  20,  19),  71.0 :  +177.5,  10.1,  100.0
BikJump v2.01                   :    100 (  61,  22,  17),  72.0 :  +198.9,  10.7,  100.0
Matheus-2.3                     :    100 (  66,  19,  15),  75.5 :  +220.5,  10.7,  100.0
Monarch 1.7                     :    100 (  72,  12,  16),  78.0 :  +245.5,  11.0,  100.0
BigLion 2.23w                   :    100 (  82,   7,  11),  85.5 :  +277.1,   9.4,  100.0
Sharper 0.17                    :    100 (  83,   7,  10),  86.5 :  +289.8,  10.8,  100.0
Feature Category Date Build Number WAC1 ELO Rating2 Improvement
Rook And Queen On 7th Rank Evaluation 2015 Aug 20 123 279 2307 +20
Knight Outposts Evaluation 2015 May 27 83 276 2287 +25
Tune Reductions And Pruning Search 2015 Apr 26 74 275 2262 +20
Bishop Pair Evaluation 2015 Apr 15 72 275 2242 +18
Free Passed Pawns Evaluation 2015 Mar 10 59 270 2224 +31
Unstoppable Pawns
Draws, Material Trades
Evaluation 2015 Jan 31 52 270 2193 +39
Late Move Pruning Search 2015 Jan 10 44 273 2154 +39
History Heuristic
Late Move Reductions
Search 2015 Jan 04 43 275 2115 +50
Killer Moves Search 2015 Jan 03 38 275 2065 +61
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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