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This is version 3.0 of Amoeba. It finally supports parallel search using the lazy smp approach.
On single core, I expect Amoeba 3.0 to be sightly stronger than Amoeba 2.8 (~ 15 elo). Using 4 threads, Amoeba 3.0 should be more than 100 elo stronger than amoeba 2.8
For linux users:
The tourney manager now support usual time settings
New: postmortem is a cmd line executable allowing retro-analysis of games to spot some possible mistakes. Amoeba 3.0 search is internally available, but It can also use any UCI engines supporting the searchmoves version of the go command.
Sightly enhanced search
Evaluation function includes some bishop/pawn interaction knowledge and has been retuned.
The enhancement is modest compared to version 2.7, probably around 15 Elo.
I hope this new version to be stronger than version 2.6 by about 40 elo.
- The eval has been improved:
- take into account hanging pieces (pieces en prise), trapped pieces (pieces en prise without safe escape) and enclosed pieces (pieces without safe moves)
- better handling of pawn structures.
- king shield/storm fixed & added a feature to attract the king towards the middle of the pawns in endgame.
- Time management has been improved. Amoeba 2.7 uses more time when the search fail low and less time on some obvious moves.
Several changes has been conducted in the search part of the engine, and the following algorithms have been revisited and improved:
- transposition table.
- late move reduction (LMR)
- aspiration windows
- see pruning
- retuned weights (using more "good" games).
I hope this new version to be stronger than version 2.5 by about 20 elo.
This version should be significantly stronger than version 2.4 (by about 30 elo).
- better knowledge on rook structures.
- revisited extension / reduction
- evaluation tuned from a newer & better set of positions
The version 2.4 should be significantly stronger than the versions 2.2/2.3, with an estimated progress over 50 elo.
Both evaluation and search have been improved:
The evaluation function now takes into account the following features:
- control center
- pinned pieces
- recognize some drawish positions
The search improvements include:
- Better & faster move sorting based on insertion sort
- Enhanced history
- Late move pruning and see move pruning
The version 2.3 corrects a bug which prevented Amoeba to play under some GUI (ChessGui and Cutechess-cli).
From the command line, help display, version display and debugging output to a log file have been added.
Other changes are mostly cosmetic.
No search or eval enhancement, and the strength of this program should be the same as version 2.2 and slightly stronger than version 2.1
Minor bug removal
Slightly enhanced search & eval
Should be stronger than previous version by more than 10 elo