Drosophila

A chess engine by Gustaf Ullberg.

Introduction

Drosophila is an open source chess engine. You can use it with any chess GUI supporting the Chess Engine Communication Protocol, such as Xboard or Arena.

If you are developing a chess GUI, you also can compile the engine as a library and use it within your application.

Drosophila was earlier named Pawned.

Releases

Drosophila 1.6 - 2020-03-12

• Retuned evaluation
• Deeper futility pruning
• Handle check in quiescence search
• SEE used in move ordering
• King tropism replaced by king pressure
• Improved time management

Drosophila 1.5.1 - 2018-03-05

• Bugfix: Avoid unnecessary CPU load while waiting for input (Windows only)

Drosophila 1.5 - 2018-02-11

• Evaluation improvements
  • Better evaluation of passed pawns
  • Mobility
• Search improvements
  • Improvements to late move reduction
  • More aggressive futility pruning
  • History heuristic
  • Killer moves

Drosophila 1.4 - 2015-03-06

• Improved evaluation
  • Passed pawns
  • Isolated pawns
  • Rooks on (half-)open files
  • King tropism
  • Smooth transition between game phases
• Better detection of insufficient mating material
• Search considers 50 move rule

Drosophila 1.3 - 2015-01-24

• New name to avoid confusion with other chess engines
• SEE pruning of quiescence search
• Improved evaluation function
• Make use of null move pruning in the endgame
• Accept xboard commands during search
• Support for the xboard "?" command (move now)
• Report draws due to:
  • the 50 move rule
  • insufficient mating material
  • threefold repetition to the GUI

Pawned 1.2 - 2014-12-27

• Stability improvements (resolving illegal moves)
• New openging book
• Support for Polyglot books
• Support for incremental time controls

Pawned 1.1 - 2014-12-08

• Pondering (thinking during the opponent's turn)
• Full principal variation in thinking output
• Support for the "setboard" command
• Pawn shield
• Performance improvements

Pawned 1.0 - 2014-02-28

• First release

How to build from source code

You need a Git client, CMake and a C compiler (GCC, Clang or Visual Studio) to obtain and build the source code.

Linux, Mac OS, etc

git clone https://github.com/gustafullberg/drosophila.git
cd drosophila
mkdir build
cd build
cmake .. -DCMAKE_BUILD_TYPE=Release -G "Unix Makefiles" 
make

Windows (assuming a 64-bit build with Visual Studio 2012)

git clone https://github.com/gustafullberg/drosophila.git
cd drosophila
mkdir build
cd build
cmake .. -G "Visual Studio 11 Win64"

Now open the newly created drosophila.sln file and build from within Visual Studio.

Technical features

State representation:

• Bit-boards

Search:

• MTD(f)
• Iterative deepening
• Quiescence search with SEE pruning
• Transposition table
• Move ordering
• Null move pruning
• Futility pruning
• Late move reductions
• Pondering
• Opening book

Evaluation:

• Material
• Piece-square tables
• Mobility
• Pawns defending other pawns and minor pieces
• Pawn structure
• Rooks on (half-)open files
• King pressure
• Tempo

License

Drosophila is released under the MIT License.