Emerald Chess 0.4.1

This update does not include significant search or evaluation changes (<10 Elo change)

Updates:

1. Support UCI command go nodes
2. Shorten PV output after three-fold repetition (and makes fast-chess happier)
3. Move right away if there is an only legal move (enabled automatically only in competition mode)
4. Support Hash option (default 16, max up to 2048)
5. Now shows time, nodes per second and hash full information in output
6. Added verification search for NMP
7. Small tweaks to LMR and move ordering

Emerald Chess 0.4.0

Updates:

• A full rewrite of search algorithms. Fixed bugs and now (finally!) correctly works with history & killer heuristics.
• An update to the MovePicker class. Now it won't generate all moves at once, making the engine even faster.
• A brand-new NNUE for evaluation. Please find more details in README.

Performance:
Beats previous version with around 91% win rate (i.e. roughly +402 Elo improvement).

Against other opponents:

Opponent	Version	CCRL Blitz Elo	Elo difference
Neuromancer	1.5	1828	+173
Cadabra	2.0.0	1960	+155
Lynx	0.16.0	1970	+250
Blunder	5.0.0	2014	+200
Stash	15.3	2170	+61
Oxide	1.0.0	2238	-264

Estimated Elo: 2100 2211 +/- 20 CCRL blitz scale

All games tested under 10+0.1 time control; played 60 games against each opponent (so the results are not necessarily reliable; the actual outcome may be quite different).

Note: Requires AVX2 and FMA3 support. This should not be a problem for reasonably new CPUs.

Emerald Chess 0.3.0

Updates:

• Static Exchange Evaluation (SEE) implemented
• Late Move Reduction (LMR)
• SEE pruning
• Tuned evaluation and other constants

Performance:

• ~200 Elo improvement compared to version 0.2.0 (Time control 10+0.1)

Note: The binary build requires AVX2 instruction support from CPU. This normally should not cause an issue.

Emerald Chess 0.2.0

Updates:

• Fully refactored search code
• Introduced aspiration window
• A Stockfish-inspired evaluation function

Test result:

• ~147 Elo boost compared to previous version
• ~23 Elo higher than Shallow Blue 2.0.0

Both tested under 10s+0.1s time control.

Emerald Chess 0.1.1

Minor updates:

• Show version message in UCI and on start up
• Insignificant time management update
• Provide binary that can run on machines with AVX512 support (skylake)

Emerald Chess 0.1.0

The starting point of Emerald chess engine!

Features:

• Principal Variation Search
• Transposition table (not configurable)
• Quiescence search
• Piece square table, mobility, basic pawn structure knowledge in evaluation
• MVV/LVA and killer heuristic in move ordering
• Iterative deepening

Playing strength: estimated ~1600 Elo