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MadChess 2.0 Beta Build 044 (Late Move Pruning)

By Erik Madsen January 10, 2015 at 2:01 PM February 5, 2022 at 9:27 PM Code

I added late move pruning to MadChess 2.0 Beta. Moves are sorted according to the history heuristic. If a quiet move qualifies for the largest late move reduction, but is less than or equal to four moves from the search horizon, it is skipped. The move is very unlikely to cause a beta cutoff and no time is wasted searching it.

This added 39 Elo to the playing strength of MadChess 2.0 Beta. MadChess 2.0 Beta is now stronger than MadChess 1.4.

MadChess 2.0                   2154 :    800 (+347,=162,-291),  53.5 %

vs.                                 :  games (   +,   =,   -),   (%) :   Diff,  SD, CFS (%)
Glass 1.6                           :     50 (   4,   2,  44),  10.0 :   -281,  27,    0.0
Sungorus 1.4                        :     50 (  14,  16,  20),  44.0 :   -156,  12,    0.0
Capivara LK 0.09a01a                :     50 (   9,  14,  27),  32.0 :   -153,  16,    0.0
Mediocre v0.34                      :     50 (  13,   8,  29),  34.0 :    -63,  15,    0.0
FireFly v2.6.0                      :     50 (  20,  13,  17),  53.0 :    -46,  14,    0.0
ZCT 0.3.2450                        :     50 (  20,  11,  19),  51.0 :    -43,  15,    0.2
Jazz v444                           :     50 (  12,   9,  29),  33.0 :    -39,  13,    0.1
Wing 2.0                            :     50 (  19,   9,  22),  47.0 :    +31,  14,   98.9
BikJump v2.01                       :     50 (  20,  12,  18),  52.0 :    +58,  14,  100.0
Matheus-2.3                         :     50 (  21,  12,  17),  54.0 :    +76,  14,  100.0
Monarch 1.7                         :     50 (  27,  11,  12),  65.0 :   +106,  14,  100.0
BigLion 2.23w                       :     50 (  33,   6,  11),  72.0 :   +133,  12,  100.0
Sharper 0.17                        :     50 (  34,  10,   6),  78.0 :   +147,  13,  100.0
Faile 1.4                           :     50 (  30,  11,   9),  71.0 :   +174,  12,  100.0
Jabba13032012                       :     50 (  36,   7,   7),  79.0 :   +204,  13,  100.0
Roce 0.0390                         :     50 (  35,  11,   4),  81.0 :   +273,  12,  100.0

Feature	Category	Date	Rev¹	WAC²	Elo Rating³	Improvement
Late Move Pruning	Search	2015 Jan 10	44	273	2154	+39
History Heuristic Late Move Reductions	Search	2015 Jan 04	40	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	34	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	–

Subversion source code revision
Win At Chess position test, 3 seconds per position
Bullet chess, 2 min / game + 1 sec / move

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