This is a FREE UCI-compatibile chess engine. It is a fork of cfish.
Thanks to Norman Schidt and Albert Sliver for inspiration on creating my own fork of Stockfish. Also big thanks to Robert Houdart for great optimization ideas, overall making the engine almost 20% faster!
This engine uses a HalfKAv2-2048x2-64-64-1 evaluation network, which contains whopping 4 times the knowledge of Stockfish 14. It was trained partially on Lc0 data, which gives it a unique positional style, while still preserving the tactical sharpness of Stockfish. The network was trained using a modification of the state-of-the-art NNUE trainer, utilizing publicly available datasets 1, 2, 3
Due to the large size the release is available only on google drive here. It includes Windows and Linux binaries for all supported architectures, along with the network. This is the only place where the network can be found.
- Polyglot support
- Anarchy mode
setoption name Anarchy value true- makes en-passant forced
- 64-bit hash key
- reduces the amount of hash collisions and allows for more robust long analysis
- resizing the transposition table preserves the contents as much as possible
- Persistent transposition table
setoption name PersistentTTMinDepth value 4(min 0, max 255). The minimum entry depth to store/load.setoption name PersistentTTFileName value filename.ptt. The file which contains the persisted TT. Doesn't do anything on itself.setoption name PersistentTTSerialize. Serializes the current transposition table according to the options above. The file is overwritten.setoption name PersistentTTDeserialize. Deserializes the current transposition table according to the options above. Only worse entries are replaced.
Compiling Fat Titz requires a working gcc or clang environment. The MSYS2 environment is recommended for compiling Fat Titz on Windows (see below on how to set up MSYS2).
To compile, type:
make target [ARCH=arch] [COMP=compiler] [COMPCC=gcc-4.8] [further options]
from the src directory. Lists of supported targets, archs and compilers can be viewed by typing make or make help.
If the ARCH variable is not set or is set to auto, the Makefile will attempt to determine and use the optimal settings for your system. If this fails with an error or gives unsatisfactory results, you should set the desired architecture manually. The following ARCH values are supported: x86-86-modern, x86-64-avx2, x86-64-bmi2, x86-64-avx512, x86-64-avx2-vnni, x86-64-bmi2-vnni, x86-64-avx512-vnni. SSSE3 support is required, if your cpu does not support SSSE3 then see here.
Be aware that a Fat Titz binary compiled specifically for your machine may not work on other (older) machines. If the binary has to work on multiple machines, set ARCH to the architecture that corresponds to the oldest/least capable machine.
Further options:
pure=yes | NNUE pure only (no hybrid or classical mode) |
numa=no | Disable NUMA support |
lto=yes | Compile with link-time optimization |
extra=yes | Compile with extra optimization options (gcc-7.x and higher) |
Add numa=no if compilation fails withnuma.h: No such file or directory or cannot find -lnuma.
The optimization options currently enabled with extra=yes appear to be less effective now that the NNUE code has been added.
Enable/disable anarchy mode. In anarchy mode en-passant is forced. Disabled by default
Controls the minimum depth of serialized TT entries
Path for the persistent TT operations.
Serializes the TT, see "Additional features" for more.
Deserializes the TT, see "Additional features" for more.
By default, contempt is set to zero during analysis to ensure unbiased analysis. Set this option to White or Black to analyse with contempt for that side.
The number of CPU threads used for searching a position.
The size of the hash table in MB.
Clear the hash table.
Let Fat Titz ponder its next move while the opponent is thinking.
Output the N best lines when searching. Leave at 1 for best performance.
Compensation for network and GUI delay (in ms).
Increase to make Fat Titz use more time, decrease to make Fat Titz use less time.
Path to the folders/directories storing the Syzygy tablebase files. Multiple directories are to be separated by ";" on Windows and by ":" on Unix-based operating systems. Do not use spaces around the ";" or ":".
Example: C:\tablebases\wdl345;C:\tablebases\wdl6;D:\tablebases\dtz345;D:\tablebases\dtz6
Minimum remaining search depth for which a position is probed. Increase this value to probe less aggressively.
Disable to let fifty-move rule draws detected by Syzygy tablebase probes count as wins or losses. This is useful for ICCF correspondence games.
Limit Syzygy tablebase probing to positions with at most this many pieces left (including kings and pawns).
Use Syzygy DTM tablebases (not yet released).
Control PolyGlot book usage.
Name of NNUE network file.
By default, Fat Titz uses NNUE in Stockfish's Hybrid mode, where certain positions are evaluated with the old handcrafted evaluation. Other modes are Pure (NNUE only) and Classical (handcrafted evaluation only).
Control allocation of the hash table as Large Pages (LP). On Windows this option does not appear if the operating system lacks LP support or if LP has not properly been set up.
This option only appears on NUMA machines, i.e. machines with two or more CPUs. If this option is set to "on" or "all", Fat Titz will spread its search threads over all nodes. If the option is set to "off", Fat Titz will ignore the NUMA architecture of the machine. On Linux, a subset of nodes may be specified on which to run the search threads (e.g. "0-1" or "0,1" to limit the search threads to nodes 0 and 1 out of nodes 0-3).
- Download and install MSYS2 from the MSYS2 website.
- Open an MSYS2 MinGW 64-bit terminal (e.g. via the Windows Start menu).
- Install the MinGW 64-bit toolchain by entering
pacman -S mingw-w64-x86_64-toolchain. - Close the MSYS2 MinGW 64-bit terminal and open another.