Nemorino is a UCI chess engine.
- Syzygy Tablebase support
- Pondering
- Standard Chess and Chess960
- Multi Core support (Shared Hash Table)
- Multi PV analysis mode
- CECP support (experimental - all testing is done using UCI)
- UCI_Chess960: If set to true engine will play according to Chess960 rules (default false)
- Hash: Size in MBytes used for the transposition table (default is 32. Nemorino will use additional memory for other fixed-size hash tables)
- Clear Hash: Will clear the transposition table
- MultiPV: Number of principal variations shown (default 1)
- Threads: Maximum number of threads (cores) used (default determined by number of available hardware threads)
- Ponder: When set to true, engine will continue analysis while waiting for opponent's move (default false)
- Contempt: Score (in centipawns) for accepting draws. If Contempt > 0 then the engine will avoid draws (default 0)
- BookFile: Polyglot book file the engine shall use (default "book.bin"). Nemorino doesn't have an own book so far
- OwnBook: Use Polyglot book, specified by book file (default false)
- SyzygyPath: Path(es) to directories Syzygy tablebase files can be found. Seperate multiple directories by ';' on windows and by ':' on linux
- SyzygyProbeDepth: Minimum search depth for probing Syzygy Bases. The lower the number, more tablebase lookups will be done, but search speed will decrease (default 8)
- MoveOverhead: Safety Time(in ms) needed to avoid time-losses (default 100)
- UCI_Opponent: With this command the GUI can send the name, title, elo and if the engine is playing a human or computer to the engine (see UCI Specification)
Released executables can be downloaded in the Download section
The current development versions are also available:
Nemorino doesn't bring it's own UI. So for running it, you need a GUI supporting UCI (like Arena).
The engine requires 64-bit Windows.
- Bitboard based (using magic bitboards for sliding move generation)
- Principal Variation Search (with Aspiration Windows, Null-Move Pruning, Killermoves, Futility Pruning, Razoring, ...)
- Tapered Eval based on Material, Mobility, Threats, King Safety, and Pawn Structure
- Special evaluation functions for some endgames
- Copy/Make
1.01:
-
Bugfix: rare crashes caused by hash collisions in transposition table -
Code changes for non-popcount compiles
1.02:
-
New Parameters: SyzygyProbeDepth and MoveOverhead -
Bugfix: Handling of EP-Squares in TB probing code
2.00:
-
Several Improvements in Search: Singular Extensions, Cut Node Extensions, improved IID,.. -
Improved SEE (consider promotions and pinned pieces) -
Improved King Safety Evaluation -
Scale down endgame values if there are opposite colored bishops -
Several minor improvements and clean-ups
2.00a (only bugfixes relevant when running with more than one thread):
-
Fix for known issue with tablebase access (see https://github.com/basil00/Fathom/issues/15 -
Fix for other (rare) crashes
3.00:
-
Refactoring of SMP implementation => Improved stability -
Several minor improvements in search and move ordering
4.00:
-
Improved King Safety evaluation -
Some Improvements when running with many threads -
Some Evaluation Improvements (added some material imbalance terms, knight center mobility, ... and removed some useless terms)
5.00:
-
Several minor Improvements especially for King Safety -
Several Bugfixes -
Replaced Syzygy probing code. Now instead of Fathom library, probing code from Stockfish is used
GNU GENERAL PUBLIC LICENSE Version 3
Nemorino is listed in several rating lists:
Nemorino 5.00
- CCRL 40/40 (4 CPU) Elo 3161 #17
- CCRL 40/40 Elo 3084 #21
- CCRL 40/4 (4 CPU) Elo 3178 #25
- CCRL 40/4 Elo 3123 #21
- CCRL 40/4 (FRC) Elo 3180 #9
- FastGM Bullet Elo 2921 #24
- FastGM 10min Elo 2971 #18
- CEGT 40/4 Elo 2974 #23
- CEGT 40/20 Elo 2992 #21
- Owl Chess Elo 3097 #21
Nemorino 4.00
I wrote this engine because I wanted to understand, how a chess engine is working. And the best way to learn is to write an engine from scratch by yourself. I first started with C#, but after some time I got the ambition to learn C++. Therefore don't expect a lot of new ideas within my code, and neither expect clean and well-structured code. Instead you will find a unique combination of all those ideas explained in the Chess Programming Wiki.
These are my sources of information I used for my engine:
- My main source of information: Chess Programming Wiki
- Computer Chess Club Forums
- The code of several Open Source Chess Engines, mainly:
- Stockfish - I copied board and move representation and some lines of code from Stockfish (marked by source code comments)
- Hakkapeliitta
- Lozza
- Senpai
- The blogs of Steve Maughan, Thomas Petzke and Jonatan Pettersson