Halogen

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[ Br···O halogen bonds [1] Halogen,

an UCI compliant open source chess engine by Kieren Pearson, written in C++, licensed under the GPL v3 and first released on GitHub in June 2019 [2]. Since version 7 in September 2020, Halogen features an own, incrementally updated neural network for its evaluation function, inspired by Stockfish NNUE. Halogen 8 features a larger network than Halogen 7, but runs significantly faster due to improvements and optimisations, best if compiled for AVX2 instructions. Its development and testing was supported on the OpenBench framework. Networks are trained through a private, from scratch C implementation created in collaboration with Andrew Grant [3].

Features#

[4]

Board Representation

• Bitboards
• Legal Move Generation by Tinker’s Approach

Search

• Iterative Deepening
• Aspiration Windows
• Lazy SMP
• NegaScout
• Transposition Table
  • Shared Hash Table
  • Zobrist Hashing
• Move Ordering
  • Hash Move
  • SEE for Captures
  • Killer Heuristic
  • History Heuristic
• Selectivity
  • Check Extensions if SEE >= 0 or PV
  • Passed Pawn Extensions (7th, 2nd rank)
  • Null Move Pruning
  • Mate Distance Pruning
  • Futility Pruning
  • Late Move Reductions
  • Quiescence Search

Evaluation

• Evaluation Hash Table
• NNUE (>= Halogen 7)

Misc#

• Syzygy Bases

Forum Posts#

2019#

• Requirements for a new chess engine by Kieren Pearson, CCRL Discussion Board, December 09, 2019
• Re: New engine releases 2019 by Günther Simon, CCC, December 22, 2019 » Halogen 2.7.3

2020 …#

• Re: New engine releases 2020 by Gabor Szots, CCC, January 06, 2020 » Halogen 3.0
• Halogen 4 release by Kieren Pearson, CCRL Discussion Board, June 22, 2020
• Re: New engine releases 2020 by Kieren Pearson, CCC, June 22, 2020 » Halogen 4
• Re: New engine releases 2020 by Kieren Pearson, CCC, July 14, 2020 » Halogen 5
• Re: New engine releases 2020 by Kieren Pearson, CCC, August 12, 2020  » Halogen 6
• Re: New engine releases 2020 by Kieren Pearson, CCC, September 22, 2020  » Halogen 7
• Re: New engine releases 2020 by Kieren Pearson, CCC, October 27, 2020 » Halogen 8
• Halogen questions by Günther Simon, CCC, November 01, 2020
• Re: New engine releases 2020 by Kieren Pearson, CCC, November 11, 2020 » Halogen 8.1
• Re: Speculations about NNUE development (was New engine releases 2020) by Connor McMonigle, CCC, November 12, 2020 » Dragon by Komodo Chess, Seer

Re: Speculations about NNUE development (was New engine releases 2020) by Connor McMonigle, CCC, November 12, 2020

• Re: will Tcec allow Stockfish with a Leela net to play? by Connor McMonigle, CCC, June 17, 2021 » NNUE

External Links#

Chess Engine#

• GitHub - KierenP/Halogen: A c++ chess engine
• Halogen in CCRL Blitz

Misc#

• halogen - Wiktionary
• Halogen from Wikipedia
• Halogen (disambiguation) from Wikipedia
• Halogen lamp from Wikipedia
• Halogen - The Letter, Sirens (2006), YouTube Video

References#

1. ↑ Packing of silsesquixane molecules in crystal lattice including Br···O halogen bonds, Image by Wisznu101, May 21,2018, Wikimedia Commons
2. ↑ Release Halogen 2.3 · KierenP/Halogen · GitHub
3. ↑ Halogen/README.md at master · KierenP/Halogen · GitHub
4. ↑ Features based on Release Halogen 8 · KierenP/Halogen · GitHub

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