ArGO v1.0.0

Major Release Highlights

This first major release of the ArGO chess engine marks a significant milestone with substantial improvements in playing strength, stability, and performance. The engine now incorporates a fully-functional NNUE evaluation system and sophisticated search techniques that bring it to a competitive level.

New Features

• NNUE Evaluation System: Implemented an Efficiently Updated Neural Network for position evaluation, ported from Koivisto
• Advanced Time Management: Dynamic time allocation based on position complexity and search stability
• Improved Search Algorithms:
  • Principal Variation Search (PVS) for more efficient alpha-beta pruning
  • Enhanced Late Move Reduction with dynamic depth adjustments
  • Null move pruning for quick detection of strong positions
• Transposition Table Enhancements:
  • Age-based replacement strategy
  • Improved hash entry utilization
• Magic Bitboards: Optimized move generation for sliding pieces with perfect hashing
• Check Extensions: Automatic search depth extension in check positions
• Mate Distance Pruning: Early termination for detected forced mates

Performance Improvements

• Assembly Optimizations: Critical NNUE calculations using hand-tuned assembly for AMD64
• Move Ordering Refinements:
  • Fine-tuned MVV-LVA capture scoring
  • Improved history heuristic scaling
  • Better killer move selection
• Reduced Memory Footprint: More efficient data structures for core components
• Cache-Friendly Data Layouts: Restructured critical arrays for better cache utilization

UCI Compliance

• Full UCI Protocol Support: Compatible with standard chess GUIs
• Configurable Options: Hash size, threads, and other engine parameters
• Detailed Search Information: Proper reporting of depth, score, nodes, and principal variation

Technical Documentation

• Added comprehensive documentation for all major engine components
• Detailed explanations of core algorithms and data structures
• Architecture overview and design principles

Bug Fixes

• Fixed evaluation inconsistencies in endgame positions
• Corrected castling detection in certain edge cases
• Resolved issues with en passant capture generation
• Fixed time management in tournament time controls
• Eliminated memory leaks in long-running searches

Known Limitations

• NNUE assembly optimizations only available on Linux AMD64 platforms
• No multi-threaded search implementation yet
• No endgame tablebase support

Future Plans

• Three-fold repetition check
• Move Generation through iterators
• Aspiration windows
• Updated Transposition Table and Reduction Table
• Refactoring the board implementation for easier move making
• Multi-threaded search
• Syzygy tablebase integration
• NNUE training infrastructure
• More configurable search and evaluation parameters

v0.4.0

Argo V0.4.0

Features Added

• Implemented history heuristics for improved move ordering of quiet moves
• Added killer move tables (2 killers per ply)
• Added Late Move Reduction ( only 1 at the moment)
• Fix Evaluation Bug

Technical Details

• History table tracks successful quiet moves by piece movement (from-to squares)
• Killer moves store non-capturing moves that cause beta cutoffs
• Move ordering priority:
  • Transposition table moves
  • Capturing moves (MVV-LVA)
  • Killer moves
  • History moves

Known Issues

• Current move ordering score scaling may need adjustment
• History score updates might be too aggressive with depth^2 bonus
• Memory usage increased due to history tables

v0.3.1

Argo v0.3.1

Fixes

• Fix time management issues that made the engine take more time than allowed

v0.3.0

Argo v0.3.0

Major Features

• Transposition Table implementation
• Move ordering improvements with TT moves
• Enhanced search with memory
• Better time management integration

Technical Improvements

• Zobrist hashing implementation
• TT probing and storing in search
• Memory-efficient position caching
• Search speed improvements via caching

Performance

• Faster search through position caching
• Better move ordering leading to more pruning
• Reduced redundant search in transpositions
• Search depth improvements through better time usage

Known Limitations

• Basic move ordering (only TT moves)
• No killer moves or history heuristic yet
• Basic endgame handling
• Simple evaluation function
• Poor time management
• Draw by repetition even while ahead.

v0.2.0

Argo v0.2.0

Features

• Alpha-beta search implementation
• Basic time management
• UCI protocol compliance
• Bitboard board representation
• Move generation with legal move checking
• Basic evaluation function

Performance

• Search depth: Reaches depth 6-7 in middlegame
• NPS (Nodes Per Second): ~2.7-3.0 million
• Time management for classical time controls

Known Limitations

• Basic endgame handling
• No tablebase support
• Simple evaluation function
• Basic move ordering

v0.1.0

First release of Argo Chess Engine v0.1.0

The engine has no search or evaluation, it just outputs a random move after 500ms delay.

Features:

• UCI protocol support
• Basic move generation
• Random move selection

Binaries available for:

• Linux (amd64, arm64)
• Windows (amd64)
• macOS (amd64, arm64)