Mantissa

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Mantissa,
an UCI compatible open source chess engine by Jeremy Wright, written in Rust, licensed under the GPL v3.0, first released in September 2021 ¹. Supported by Zahak author Amanj Sherwany, Mantissa v3.0.0, released in December 2021, came with an NNUE implementation of a 769 -> 128 -> 1 net topology. In Mantissa v3.3.0, released in January 2022, the net topology was changed due to an inspiration from reading Koivisto's source code, considering board symmetry. Now instead of a 769th feature for side to move, the new net uses 2 sets of 128 neurons in the hidden layer with mirrored weights to reflect the game from the point of views of both sides.

Selected Features

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Board Representation

• Bitboards
• Magic Bitboards

Search

• Iterative Deepening
• Aspiration Windows
• Lazy SMP
• Principal Variation Search
• Transposition Table
• Selectivity
  • Null Move Pruning
  • Late Move Reductions
  • Late Move Pruning
  • Futility Pruning
  • Reverse Futility Pruning
  • Singular Extensions
  • Multi-Cut
  • Quiescence Search
  • SEE Pruning
• Move Ordering
  • MVV-LVA
  • Killer Heuristic
  • History Heuristic
  • Countermove Heuristic

Evaluation

• NNUE (v3.0.0)
• Tapered Evaluation
• Material
• Bishop Pair
• Piece-Square Tables
• Mobility
• Rook on Seventh
• Rook on (Semi) Open File
• Pawn Structure
  • Pawn Hash Table
  • Doubled Pawn
  • Isolated Pawn
  • Backward Pawn
  • Advanced Connected Pawns
  • Passed Pawns
• King Safety

Forum Posts

• New Engine: Mantissa by Jeremy Wright, CCRL Discussion Board, September 19, 2021
• Mantissa 3.0.0 by Jeremy Wright, CCC, December 10, 2021
• Re: New engine releases & news H1 2022 by Jeremy Wright, CCC, January 11, 2022

External Links

Chess Engine

• GitHub - jtheardw/mantissa: Chess Engine
• Mantissa at CCRL 40/15

Misc

• Mantissa from Wikipedia
• Common logarithm from Wikipedia
• Significand from Wikipedia
• Mantissa - Land of The Living (1992), YouTube Video

Watch on YouTube

References