Chess Engine for CS 340: Artificial Intelligence class at OWU

A Python-based chess engine implementation featuring player vs. player gameplay and AI opponents using minimax and alpha-beta pruning algorithms.

Features

• Complete chess rule implementation including:
  • All standard piece movements
  • Special moves (castling, en passant, pawn promotion)
  • Check and checkmate detection
  • Stalemate detection
• Multiple game modes:
  • Player vs Player
  • Player vs AI (Basic Minimax)
  • Player vs Enhanced AI (Alpha-Beta Pruning)
• Console-based chess board visualization
• Piece-position evaluation tables for intelligent AI gameplay
• Advanced board evaluation with multiple heuristics

Implementation Details

Chess Pieces

The engine uses an object-oriented approach with a ChessPiece parent class and individual classes for each piece type:

• Pawn
• Rook
• Knight
• Bishop
• Queen
• King

Each piece implements its own valid_moves() method defining legal movements according to chess rules.

Board Representation

• 8x8 grid implemented as a 2D array
• Algebraic notation support (e.g., "e2 e4")
• Piece positions tracked with coordinate system (0-7, 0-7)

AI Implementation

Basic Chess Bot

• Uses Minimax algorithm
• Configurable depth for move searching
• Basic position evaluation

Improved Chess Bot

• Implements Alpha-Beta Pruning
• Deeper search depth capability
• Enhanced evaluation function including:
  • Piece-square tables
  • Material value
  • Position evaluation
  • Special bonuses/penalties for:
    • Doubled pawns
    • Isolated pawns
    • Bishop pairs
    • Knight positioning

Evaluation Function

The engine uses sophisticated position evaluation including:

• Base piece values
• Position-dependent scoring using piece-square tables
• Tactical considerations:
  • Pawn structure analysis
  • Bishop pair bonus
  • Knight positioning relative to pawn structure

Usage

Starting the Game

if __name__ == "__main__":
    play_chess_with_improved_ai()  # For AI game
    # or
    play_chess()  # For PvP game

Making Moves

Moves are input using algebraic notation:

Enter your move (e.g., 'e2 e4'): e2 e4

Game Modes

1. Player vs Player:

play_chess()

2. Player vs Basic AI:

play_chess_with_ai()

3. Player vs Improved AI:

play_chess_with_improved_ai()

Technical Details

Move Validation

• Legal move checking for all pieces
• Check detection and prevention
• Move simulation for check prevention
• Special move validation

Board Evaluation Metrics

• Piece Values:
  • Pawn: 100
  • Knight: 320
  • Bishop: 330
  • Rook: 500
  • Queen: 900
  • King: 20000

Position Tables

The engine uses piece-square tables for position evaluation, considering:

• Pawn advancement and structure
• Knight centralization
• Bishop diagonal control
• Rook positioning
• Queen mobility
• King safety

Future Improvements

Potential enhancements could include:

• GUI implementation
• Opening book integration
• Endgame tablebase support
• Move time control
• ELO rating system
• PGN game notation support

Dependencies

• Python 3.x
• Standard library modules:
  • copy (for board state management)