Improving Stockfish Chess Engine

Introduction

• Stockfish is the world's strongest chess engine.
• Recent improvements have been made, resulting in increased Elo ratings.
• Stockfish uses deep analysis and a neural network to evaluate chess positions.

Chess Position Analysis

• Neural Network: Used for initial evaluation, mimicking human thought processes.
  • Originally random, learned from millions of chess positions.
  • Speed improvements to the neural network were implemented.
• Search Tree: Structures potential future positions in a tree format.
  • Each node represents a future position with possible moves.

Minimax Algorithm

• Purpose: Calculates optimal player moves based on opponent's potential responses.
• Depth Parameter: Controls how deep the engine searches the tree.
  • Depth decreases with each step into the tree.
  • At depth zero, a static evaluation is used.

Late Move Reduction

• Ranking Moves: Stockfish ranks moves from best to worst.
  • Poorly ranked moves have decreased search depth.
  • Reduction size grows as confidence in a move's poor quality increases.
• Reduction Calculation:
  • Involves multiplying a constant by functions of depth and move ranking.
  • After a reduced search, promising moves undergo full search verification.
• Testing Method:
  • Low-effort initial tests followed by rigorous tests for promising changes.

Recent Improvements

• Dynamic Reduction Adjustment:
  • Adjusts reduction based on position info and statistical move data.
  • Increases reduction for non-capturing moves when the best move captures.
• Analyzing Future Moves:
  • Recent changes allow consideration of post-move outcomes for reduction.
  • Static evaluation changes indicate whether to increase or decrease search depth.
• Code Enhancements:
  • Simplified conditions and streamlined code for better performance.
  • Addressed potential dangerous side effects by careful implementation.

Conclusion

• Achieved significant Elo gains, translating to high performance improvements.
• Emphasis on simplifying code while retaining functionality.
• Future directions include further tuning and testing for enhanced capabilities.

Additional Resources

• Linked videos and playlist for further exploration of Stockfish improvements.

Thank you for the support and engagement with this project!