Chess4j

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chess4j,

an open source chess engine by James Swafford using Java based technologies and the Chess Engine Communication Protocol, released under the MIT License, and first published in September 2012 [1]. The engine was hosted on SourceForge, and meant to be a test bed for various interests, including experimenting with different JVM based languages, parallel and distributed programming techniques, and machine learning. Since version 3.2 released in March 2017, chess4j became a bitboard engine, using magic bitboards to generate moves [2], now hosted on GitHub.

Features#

Board Representation

• Bitboards
• Magic Bitboards

Search

• Iterative Deepening
• Aspiration Windows
• Alpha-Beta
• Transposition Table
• Move Ordering
  • Hash Move
  • Killer Heuristic
  • MVV/LVA
• Selectivity
  • Check Extensions
  • Null Move Pruning with Null Move Pruning#ZugzwangVerification Zugzwang Detection
  • Late Move Reductions
  • Futility Pruning
  • Extended Futility Pruning
  • Quiescence Search
  • SEE Pruning

Evaluation

• Material
• Piece-Square Tables
• Rook on Open File
• Rook/Queen on Seventh
• King Safety
  • Pawn Shelter
  • Knight/King Tropism
• Pawn Structure
• Pawn Hash Table
  • Doubled Pawn
  • Isolated Pawn
  • Passed Pawn

See also#

• Prophet

Forum Posts#

2012 …#

• Mr.James Swafford and Chess4J project by Ruxy Sylwyka, CCC, September 11, 2012
• Chess4J 2.0 is out ! by Ruxy Sylwyka, CCC, June 10, 2014

2015 …#

• chess4j 3.0 is released by James Swafford, CCC, January 16, 2016
• chess4j 3.1 released by James Swafford, CCC, February 12, 2017
• chess4j 3.2 is released (and it’s magic) by James Swafford, CCC, March 11, 2017
• hashing in chess4j by James Swafford, CCC, December 30, 2017 » Transposition Table
• chess4j 3.4 by James Swafford, CCC, July 27, 2018
• chess4j 3.5 by Gabor Szots, CCC, December 18, 2018

2020 …#

• Prophet 4.0 and chess4j 4.0 are released by James Swafford, CCC, October 02, 2021

External Links#

• GitHub - jswaff/chess4j: a Java based chess engine [3]
• chess4j | James Swafford Blog
• Chess4j in CCRL 40/4

References#

1. ↑ chess4j 1.0 is released! by James Swafford, September 15, 2012
2. ↑ chess4j 3.2 is released (and it’s magic) by James Swafford, CCC, March 11, 2017
3. ↑ Re: chess4j 3.2 is released (and it’s magic) by Günther Simon, CCC, November 16, 2017

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