kobra 2.1

This release includes an original, updated & improved NNUE evaluation module

+65 in 10000 ultra-fast (1000ms+100ms) self-play games vs kobra 2.0.exe

VERSION	RATING	GAMES	WIN	DRAW	LOSS	WIN%	ELO	ERR	LOS
kobra 2.1	3148	10000	+3433	=4960	-1607	59.1%	+65	+/-3	100.0%
kobra 2.0	3083	10000	+1607	=4960	-3433	40.9%	-65	+/-3	0.0%

This ultra-fast testing result likely indicates a strength improvement of ~40 Elo in longer time controls.
A fast optimized avx2 binary with embedded NNUE for Windows is available below.

kobra 2.0

This release includes an original, updated & improved NNUE evaluation module

+99 in 10000 ultra-fast (1000ms+100ms) self-play games vs kobra 1.2.exe

VERSION	RATING	GAMES	WIN	DRAW	LOSS	WIN%	ELO	ERR	LOS
kobra 2.0	3083	10000	+4402	=4004	-1594	64.0%	+99	+/-3	100.0%
kobra 1.2	2984	10000	+1594	=4004	-4402	36.0%	-99	+/-3	0.0%

Fast, optimized binaries with embedded NNUE, for Windows, Linux, and Android (compiled by Jim Ablett...Thx!) are available below.

kobra 1.2

This release includes an original, updated & improved embedded NNUE evaluation module

+119 in ultra-fast self-play games vs kobra 1.1.exe

VERSION	RATING	GAMES	WIN	DRAW	LOSS	WIN%	ELO	ERR	LOS
kobra_1.2	2984	10000	+5095	=3068	-1837	66.3 %	+119	+/-3	100.0%
kobra_1.1	2865	10000	+1837	=3068	-5095	33.7 %	-119	+/-3	0.0%

kobra 1.1

This release includes an original, updated & improved embedded NNUE evaluation module

+130 in ultra-fast self-play games vs kobra 1.0a.exe

VERSION	RATING	GAMES	WIN	DRAW	LOSS	WIN%	ELO	ERR	LOS
kobra_1.1	2865	30000	+17056	=6580	-6364	67.82 %	+130	+/-4	100.0%
kobra_1.0a	2735	30000	+6364	=6580	-17056	32.18 %	-130	+/-4	0.0%

kobra 1.0a

This release fixes a serious basetime + increment time control bug where the engine was playing on increment only.

features:

• windows
• 64 bit
• c++20
• alpha-beta
• nnue
• bitboards
• hash
• threads
• perft

kobra 1.0

features:

• windows
• 64 bit
• c++20
• alpha-beta
• nnue
• bitboards
• hash
• threads
• perft

kobra 0.3a

this is a maintenance release to fix a time control bug

basic search and eval
using piece square tables & material count

features:

• windows
• 64 bit
• c++20
• bitboards
• hash
• threads
• perft
• estimated Elo 2200

kobra 0.3

• no change in playing strength from kobra 0.2
• code base has been refactored according to Google formatting and naming convention

basic search and eval
using piece square tables & material count

features:

• windows
• 64 bit
• c++17
• bitboards
• hash
• threads
• perft
• estimated Elo 2150

kobra 0.2

basic search and eval
using piece square tables & material count

• windows
• 64 bit
• c++17
• bitboards
• hash
• threads
• perft
• estimated Elo 2150

kobra 0.1

no search or eval
random moves

• windows
• 64 bit
• c++17
• bitboards
• hash
• threads
• perft