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		Hakkapeliitta, an UCI compatible open source chess engine by Mikko Aarnos, written in C++11/14 and licensed under the GNU General Public License, Version 3. Hakkapeliitta is a state of the art bitboard engine, and performs Magic bitboards to determine sliding piece attacks. Despite using conditional compiled x86-64 processer instructions for bitscan, Hakkapeliitta uses Kim Walisch's forward and reverse bitscans [1]. If the processor does not support hardware popcount, Hakkapeliitta falls back to SWAR-popcount. The search uses function templates to distinguish between PV-nodes and none PV-nodes at compile time [2]. Similar, hardware popcount support is boolean template parameter of evaluation routines [3].
Hakkapeliitta [4]

Etymology

The term is probably based on the Finnish battle cry "Hakkaa päälle" ^[5], commonly translated as "Cut them down!". The Finnish cavalryman in the service of King Gustavus Adolphus of Sweden during the Thirty Years' War (1618 to 1648) were called Hackapelit, Hackapelite, Hackapell, Haccapelit, or Haccapelite in the Holy Roman Empire, in the 19th-century modified to Finnish Hakkapeliitta ^{[6] [7]}.

Features

^[8]

Search

• Iterative Deepening
• Aspiration Windows
• Principal Variation Search
• Transposition Table
• Zobrist Hashing
• Null Move Pruning
• Late Move Reductions
• Internal Iterative Deepening
• Futility Pruning
• Move Count Based Pruning
• Reverse Futility Pruning
• Razoring
• Killer Heuristic
• Relative History Heuristic
• Static Exchange Evaluation

Evaluation

• Material
• Tapered Eval
• Piece-Square Tables
• Mobility
• Pawn Hash Table
• Pawn Structure
  Backward Pawn
  Doubled Pawn
  Isolated Pawn
  Passed Pawn
• King Safety
  Pawn Shelter

Misc

• Magic Bitboards
• Perft
• Pondering (since 3.0)
• Syzygy Bases

Acknowledgements

Thanks from the author to following people or organizations ^[9]

• Chess Programming Wiki (Thanks as well)
• Talkchess
• Tord Romstad of Glaurung
• Ronald de Man
• Tord Romstad, Marco Costalba, and Joona Kiiski of Stockfish
• Robert Hyatt of Crafty
• Peter Österlund of Texel
• Authors of Ivanhoe
• Ed Schröder of Rebel and Pro Deo ^[10]
• Stef Luijten of Winglet ^[11]
• Steve Maughan of Maverick
• Tom Kerrigan of TSCP

See also

• Military

Forum Posts

• Hakkapeliitta dev 63.7 by Mikko Aarnos by Jose Mº Velasco, CCC, February 25, 2014
• Hakkapeliitta 1.0 release by Mikko Aarnos, CCC, June 22, 2014
• Hakkapeliitta 2.0 release by Mikko Aarnos, CCC, December 25, 2014
• Hakkapeliitta 3.0 release by Mikko Aarnos, CCC, June 27, 2015
• Hakkapeliitta the "STRONGEST" in tactic, new Nr1 by Frank Quisinsky, CCC, July 19, 2015

External Links

Chess Engine

• mAarnos/Hakkapeliitta · GitHub
• Hakkapeliitta in CCRL 40/4

Misc

• Hakkapeliitta - Wiktionary
• Hakkapeliitta from Wikipedia
• Hakkapeliittain Marssi from Wikipedia
• Hakkapeliitta (lehti) Wikipedia (Finnish, Paramilitary Journal 1926 - 1944)
• Mossy Rocks - Cut Em Down, YouTube Video
  

References

1. ^ Hakkapeliitta/bitboard.hpp at master · mAarnos/Hakkapeliitta · GitHub
2. ^ Hakkapeliitta/search.cpp at master · mAarnos/Hakkapeliitta · GitHub - template <bool pvNode> int Search::search
3. ^ Hakkapeliitta/evaluation.cpp at master · mAarnos/Hakkapeliitta · GitHub
4. ^ Hakkapeliitta featured on a 1940 Finnish stamp, Wikimedia Commons
5. ^ Hakkapeliitta - Wiktionary
6. ^ Hakkapeliitta from Wikipedia
7. ^ Military of the Swedish Empire - Wikipedia
8. ^ based on sources of Hakkapeliitta 2.0
9. ^ mAarnos/Hakkapeliitta · GitHub - Acknowledgements
10. ^ Inside Rebel/Prodeo by Ed Schröder
11. ^ Winglet, Writing a Chess Program in 99 Steps by Stef Luijten, Wayback Machine

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