Shallow Blue

(not Deep Blue)

A UCI chess engine written in C++11

Features

• Board representation
  • Bitboards
• Move generation
  • Magic bitboard hashing
• Search
  • Principal variation search
  • Iterative deepening
  • Quiescence search
  • Check extensions
• Evaluation
  • Piece square tables
  • Pawn structure
  • King safety
  • Bishop pairs
  • Rooks on open files
  • Mobility
  • Evaluation tapering
• Move ordering
  • Hash move
  • MVV/LVA
  • Killer heuristic
  • History heuristic
• Other
  • Zobrist hashing / Transposition table
  • Opening book support (PolyGlot format)

Building

To build on *nix:

make

You can build with debugging symbols and no optimizations using:

make debug

If you have Mingw-w64 installed, you can cross compile for Windows on Linux with:

./build_windows.sh

Tests

Catch unit tests are located in the test directory.

To build and run the unit tests, use:

make test
./shallowbluetest

To build and run the unit tests, skipping perft tests (these take a while to run), use:

make test
./shallowbluetest exclude:[perft]

Documentation

Shallow Blue's code is extensively documented with Doxygen.

To generate HTML documentation use:

doxygen

Opening Books

Shallow Blue supports PolyGlot formatted (.bin) opening books. To use an opening book, the OwnBook and BookPath UCI options must be set to true and the path to the opening book file respectively.

These options can be set from your chess GUI or the UCI interface as follows:

setoption name OwnBook value true
setoption name BookPath value /path/to/book.bin

Implemented non UCI Commands

These commands can be useful for debugging.

• perft <depth>
  • Prints the perft value for each move on the current board to the specified depth
• printboard
  • Pretty prints the current state of the game board
• printmoves
  • Prints all legal moves for the currently active player

Future Improvements

• Staged move generation
• Null move pruning
• Late move reductions

License

MIT © Rhys Rustad-Elliott