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Feb 19, 2018

README.md

Demolito

Demolito is a UCI chess engine written in C. As such, it is a command line program, which is not designed to be used directly, but instead through an UCI capable UI, such as CuteChess or Banksia, or c-chess-cli.

Versions

Version numbers are automatically generated to be the ISO date of the last commit (ie. YYYY-MM-DD).

Windows binaries

Windows binaries are automatically generated, courtesy of AppVeyor, and can be found here:

  • select the latest corresponding to the master branch. Be sure to choose master because other branches are (mostly) elo-regressive experimental garbage.
  • go to Artifacts, where you can download the (compressed) binaries.

The archive contains 3 .exe files, and this is how you choose:

  • AMD: use popcnt if it works, otherwise no_popcnt (very old machine).
  • Intel: use pext if it works, otherwise popcnt (old machine), and if that still fails then no_popcnt (very old machine).

Playing level

Demolito is easily stronger than best humans, yet still significantly below the top engines like Stockfish, Houdini or Komodo. Here are some independant rating lists:

UCI Options

  • Contempt: This is used to score draws by chess rules in the search. These rules are: 3-move repetition, 50 move rule, stalemate, and insufficient material. A positive value will avoid draws (best against weaker opponents), whereas a negative value will seek draws (best against a stronger opponent).
  • Hash: Size of the main hash table, in MB. Should be a power of two (if not Demolito will silently round it down to the nearest power of two).
  • Time Buffer: In milliseconds. Provides for extra time to compensate the lag between the UI and the Engine. The default value is just enough for high performance tools like cutechess-cli, but may not suffice for some slow and bloated GUIs that introduce artificial lag (and even more so if playing over a network).
  • Threads: Number of threads to use for SMP search (default 1 = single threaded search). Please note that SMP search is, by design, non-deterministic. So it is not a bug that SMP search results are not reproducible.
  • UCI_Chess960: enable/disable Chess960 castling rules. Demolito accepts either Shredder-FEN (AHah) or X-FEN (KQkq) notations.

Compilation

What do you need ?

  • clang or gcc
  • make
  • git

How to compile ?

In a terminal:

git clone https://github.com/lucasart/Demolito.git
cd Demolito/src
make CC=clang pext  # for Intel Haswell+ only
make CC=clang       # for AMD or older Intel

You can use gcc instead of clang, but Demolito will be a bit slower (hence weaker).

How to verify ?

Run the following benchmark:

./demolito bench|tail -4

The seal is a functional signature of the program. It must match exactly the one indicated in the last commit message. Otherwise, Demolito was miscompiled.

The rest is obvious: nodes, time, nodes per seconds (speed benchmark).