Hari: The Chess Engine

Current rating: WIP

lichess account: lichess.org/@/hari_the_chess_bot

Jump to:

1. Contributors
2. Background
3. Using the Engine
4. Architecture
5. Contributing
6. Contact

Contributors

1. Divy Patel (creator)
2. Arnav Prasad (creator)

Special mention: Jonathan Warkentin, some code was reused from his chess engine, Orion.

Background

Note: Although the engine is still being improved, a big chunk of the work is done.

The motive behind this project was to create a chess engine that can beat us, the creators, rated around 1200. We expect the engine to be able to beat us in the near future, once the engine is fully implemented. Apart from our passion for chess, we also wanted to apply the knowledge we have gained in our Software Engineering courses to a real world application. This includes the use of object-oriented programming, unit testing, concurrency, and other software engineering principles.

The project is created using Java, as it is a nice mix between C++(speed) and Python(object-oriented). It is also a language that we are both familiar with.

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Using the Engine

Using the engine currently requires Java 14 and gradle 7.5 or higher. Steps:

• Clone/download the repository to your local machine.
• Open a terminal in the root directory of the project
• Run ./gradlew clean build to create the jar file
• Use any UCI-supporting GUI to play against the engine. We recommend Arena
• Register the engine with GUI using the .jar file in the build/libs directory
• Play against the engine!

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Architecture

             -------
             | GUI |
             -------
                |
             -------
             | UCI |
             -------
                |  
            --------
            | Hari |
            --------
                |  
          ------------
          | Position |
          ------------
                |
       ------------------
       | MoveGeneration |
       ------------------
             /     \
 --------------   -----------------
 | Evaluation |   | PossibleMoves |
 --------------   -----------------

The engine is composed of:

• The UCI interface
  • communicates with the GUI
  • handles the UCI commands from GUI
  • sends the UCI commands from the engine to the GUI
• Hari
  • the engine, holds the current position
• Position
  • class that represents a chess position
  • this class is immutable
  • it contains the bitboards, the side to move, the castling rights, the en passant square, and move clocks
• Move
  • class that represents a chess move
  • this class is immutable
  • it contains the source and destination squares (as well as optional properties such as promotion piece and en passant square)
• MoveGeneration
  • generates the best next move
  • currently uses the minimax algorithm
• Evaluation
  • evaluates the board position statically
  • currently uses a simple material evaluation
• PossibleMoves
  • generates all possible moves for a given board position
  • used to generate the moves for the minimax algorithm

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Contributing to the Project

To contribute to the project, please follow the steps below:

• Browse the issues and self-assign an unassigned issue
  • Ask any questions you may have in the comments
  • Or alternatively, you can ask one of the creators via email/discord to clarify any doubts
• Open a pull request with the changes you have made
  • Make sure to include a description of the changes you have made
  • If you are fixing an issue, make sure to include the issue number in the description
  • The pull request will be reviewed by one of the creators
  • It must be approved by one of the creators and pass CI before it can be merged

Good luck and thank you for contributing to the project! As a reward, you will be added to the contributors list.

Contact

Any questions or concerns? Feel free to contact each of us at:

• Divy Patel: [email protected]
• Arnav Prasad: [email protected]

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