Chess Engines

Halogen – analysing and playing chess

Halogen is a powerful, world-class program capable of analysing and playing chess.

It is currently ranked in the top 30 chess engines.

Halogen is not a stand-alone application and should be used with any popular chess GUI that supports the UCI protocol.

Features include:

  • Uses a neural network for its evaluation function. Halogen makes use of an incrementally updated architecture, inspired by the new NNUE networks in Stockfish. Halogen features an innovative neural network implementation with an abstract architecture that allows networks to be dropped in and replaced at will. Networks are trained through a private, from scratch C implementation
  • Null-move pruning.
  • Late move reductions
  • Quiessence search, an algorithm typically used to extend search at unstable nodes in minimax game trees in game-playing computer programs.
  • Transposition table that uses Zobrist Hashing.
  • The search routine is multithreaded using the SMP parallelisation technique.

Developer: Kieren Pearson
License: GNU General Public License v3.0

Halogen development is currently supported on the Openbench framework. OpenBench is an open-source Sequential Probability Ratio Testing (SPRT) framework designed for self-play testing of engines. OpenBench makes use of distributed computing, allowing anyone to contribute CPU time to further the development of some of the world’s most powerful engines.

Halogen is written in C++. Learn C++ with our recommended free books and free tutorials.

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