Chess engine: Simbelmyne 1.4.0

 

Simbelmyne - UCI engine

Rating CEDR=2474

v.1.4.0:

Some decent improvements were made on the evaluation. Several king-safety terms

were added, and Simbelmyne now has a built-in Gradient Descent tuner for tuning

evaluation parameters.

Added features

Evaluation

Bishop pair bonus

Rook on open file bonus

Texel tuner

Piece mobility bonus

Pawn shield bonus

Virtual mobility

Search

SPSA tuning of parameters

Switch from Internal Iterative Deepening (IIR) to Internal Iterative Reduction (IIR)

Use TT in QSearch

UCI

Add Hash option for setting TT Size

Add search parameters as UCI options, for SPSA tuning

Bugfixes

Update rook eval when rook is removed.

Clear PV at the start of Qsearch, so we don't propagate up illegal moves

Fix integer overflows in RFP condition

Misc

Make move generation 100% allocation-free

Store static eval in TT entry

Prefetch TT entries

Normalize mate scores when storing in TT

Estimated rating

Self play agains v1.3.0 and against several other engines put the estimated

Elo gain at +-160, or around ~2650.

Score of Simbelmyne main vs Simbelmyne v1.3.0 (2500): 1535 - 441 - 524 [0.719]

...      Simbelmyne main playing White: 889 - 145 - 216  [0.798] 1250

...      Simbelmyne main playing Black: 646 - 296 - 308  [0.640] 1250

...      White vs Black: 1185 - 791 - 524  [0.579] 2500

Elo difference: 163.0 +/- 13.0, LOS: 100.0 %, DrawRatio: 21.0 %

2500 of 2500 games finished.

Rank Name                          Elo     +/-   Games   Score    Draw 

   0 Simbelmyne main                26       7    6000   53.8%   27.6% 

   1 Cheers 0.2 (2611)              48      19    1000   56.8%   24.0% 

   2 Leorik 2.0.2 (2536)             6      18    1000   50.8%   27.7% 

   3 Lynx 1.3 (2650)               -18      18    1000   47.4%   31.3% 

   4 Nalwald 1.9 (2625)            -31      18    1000   45.5%   30.0% 

   5 Blunder 7.6.0 (2619)          -58      18    1000   41.8%   30.9% 

   6 Avalanche 0.2.2 (2532)       -108      20    1000   34.9%   21.9% 

6000 of 6000 games finished.

Simbelmyne 1.2.0 - results:

Catto 0.1.0	4/4	+4	4 Games
Sheep 1.0	4/4	+4	4 Games
Fatalii 0.6.0	2/4	+0	4 Games
Lynx 1.2.0	0.5/4	-3	4 Games
Shuffle 5.0.0	0.5/4	-3	4 Games
RubiChess 20240112	0/4	-4	4 Games
Caissa 1.16	0/4	-4	4 Games
Counter 5.5	0/4	-4	4 Games
Minic 3.41	0/4	-4	4 Games
Avalanche 2.1.0	0/4	-4	4 Games
Texel 1.11	0/4	-4	4 Games
Uralochka 3.41 dev1	0/4	-4	4 Games
Arasan 24.1	0/4	-4	4 Games
Cheng 4.43	0/4	-4	4 Games
Pawn 3.0	0/4	-4	4 Games
Sloth 1.6	2/2	+2	2 Games
Oxidation 0.5.0	2/2	+2	2 Games
Dragonrose 0.21	1.5/2	+1	2 Games
Blocky 1.0.0	1.5/2	+1	2 Games
Pingu 3.0.0	0.5/2	-1	2 Games
Leptir 100124	0/2	-2	2 Games

Simbelmyne 1.4.0 download