Combusken

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Combusken,

an UCI compliant open source chess engine by Marcin Henryk Bartkowiak, written in the Go programming language, first released in February 2020 under the GPL 3 [1]. Already playing since April 2019 at Lichess [2], it had its tournament debut at TCEC Season 18.

Features#

Board Representation

• Bitboards
• Plain Magic Bitboards

Search

[3]

• Lazy SMP
• Iterative Deepening
• Aspiration Windows
• Alpha-Beta
• Transposition Table
• Selectivity
  • Check Extensions
  • Castling Extension
  • Singular Extensions
  • Late Move Reductions
  • Null Move Pruning
  • Futility Pruning
  • Reverse Futility Pruning
  • Late Move Pruning
  • Static Exchange Evaluation Pruning
• Move Ordering
  • Hash Move
  • Internal Iterative Deepening
  • MVV/LVA
  • Static Exchange Evaluation
  • Killer Heuristic
  • History Heuristic
  • Countermove Heuristic
  • Follow Up History

Evaluation

[4]

• Tapered Eval
• Material
• Bishop Pair
• Piece-Square Tables
• Mobility
• Outposts
• Rook on (Half) Open File
• Pawn-King Hash Table
• Pawn Structure
  • Passed Pawn
  • Isolated Pawn
  • Doubled Pawn
  • Backward Pawn
  • Straggler
  • Connected Pawns
• King Safety
  • Pawn Shield
  • Pawn Storm
  • Attacking King Zone
• Hanging Pieces
• Tempo
• Automated Tuning using Gradient Descent

Misc#

• Syzygy Bases using Fathom
• Perft

Thanks#

The author mentions following engines and their authors for implementation details and tuning positions [5]:

• CounterGo by Vadim Chizhov
• Ethereal by Andrew Grant
• Laser by Jeffrey An
• Stockfish by Tord Romstad, Marco Costalba, Joona Kiiski and Gary Linscott
• Zurichess by Alexandru Mosoi

Forum Posts#

• Re: New engine releases 2020 by Marcin Henryk Bartkowiak, CCC, February 23, 2020
• Re: New engine releases 2020 by Marcin Henryk Bartkowiak, CCC, April 06, 2020
• Re: New engine releases 2020 by Marcin Henryk Bartkowiak, CCC, October 31, 2020
• Re: Faster compiles for Intel possible for Booot & Combusken? by Marcin Henryk Bartkowiak, CCC, November 21, 2020

External Links#

Chess Engine#

• GitHub - mhib/combusken: A chess engine
• Combusken in CCRL 40/15
• ombuskengine • lichess.org

Misc#

• List of generation III Pokémon - Combusken from Wikipedia

References#

1. ↑ Re: New engine releases 2020 by Marcin Henryk Bartkowiak, CCC, February 23, 2020
2. ↑ ombuskengine • lichess.org
3. ↑ combusken/engine at master · mhib/combusken · GitHub
4. ↑ combusken/evaluation at master · mhib/combusken · GitHub
5. ↑ GitHub - mhib/combusken: A chess engine

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