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Pawn 20230120 - released - Update 2023-01-22

Updated: Jan 22

A mysterious free open source engine that is quiet on the internet and in the ratings lists...


The author of this engine, Mr Rui Coelho publishes Pawn under the GNU General Public License v3.0. And although it is available, for reasons unknown to me, only little information can be found about this chess engine.


Pawn is "a UCI alpha-beta chess engine, largely inspired by Stockfish".

Pawn is a strong "pawn" playing at around 3200 Elo!

Source: MCERL (ongoing)


It is worth adding that the source code provided by the author, is so excellently written that it allows seamless compilation for popular operating systems.

And this is commendable, because - as attentive readers of this blog have probably noticed - I like it when chess engines are available to a wide audience and chess enthusiasts.


Pawn has considerable configuration capabilities and uses advanced chess techniques, here are some information from the GitHub page:


"

UCI Options

The following UCI options are supported:

  • Hash Size of the Hash Table, in MB (defaults to 16).

  • Threads Number of threads to use during search (defaults to 1).

  • MultiPV Number of principal variations (PV) to search (defaults to 1). This should be kept at 1 for best performance.

  • Ponder Allow the engine to think during the opponent's move (defaults to false). This requires the GUI to send the appropriate go ponder.

Furthermore, the following non-standard commands are available:

  • board - show representation of the current board;

  • eval - print some of the evaluation terms;

  • test - test the move generation, transposition tables, move orderers and legality checks of the engine;

  • bench - search a set of positions to obtain a signature. Optionally, the following syntax is available: bench depth threads hash. By default, calling bench is equivalent to bench 13 1 16.

  • go perft depth - do the perft node count for the current position at depth depth.


Main Features


Board representation

  • Bitboard representation (with GCC builtin bitscan and popcount)

  • Magic numbers for slider move generation

  • Staged move generation for captures and quiet moves


Evaluation

  • Tapered evaluation

  • Material and Piece-square tables (incrementally updated)

  • Basic pawn structure

  • Mobility

  • Per-piece bonuses

  • King safety


Search

  • Principal Variation Search in a negamax framework

  • Quiescence search with SEE

  • MultiPV search

  • Transposition Tables

  • Aspiration Windows

  • Late move reductions

  • Null-move pruning

  • Singular and check extensions

  • Futility pruning

  • Mate distance pruning

  • Basic Lazy SMP threading


Move Ordering

  • MVV-LVA move ordering for captures

  • Killer moves and countermoves

  • Quiet move ordering

  • History heuristic with butterfly and piece-to boards

"


If anyone knows more about Pawn, it would be great if they shared this information in the comments section.



Feel free to download



Linux and Mac – Compiled by Darius


Pawn-20230120_Linux
.7z
Download 7Z • 3.45MB
Pawn-20230120_Mac
.7z
Download 7Z • 3.33MB


Update 2023-01-22


Due to the unstable performance of the Pawn chess engine in a Windows environment, and out of concern for user convenience, I have decided to remove this chess engine from the Files area until the author has fixed it.

I apologize for the inconvenience.


The next version of the Pawn chess engine if it runs stably in a Windows environment, then I will make this engine available for download from the Files area.





 
 

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