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Chess-Zero - Complete AlphaZero Implementation

State-of-the-art chess engine with ALL 16 expert-recommended improvements implemented.

🎉 Features

Complete AlphaZero with Modern Refinements:

  • WDL Value Head - Win/Draw/Loss prediction for better calibration
  • Teacher Distillation - Stockfish soft targets for stronger bootstrap
  • Data Augmentation - Horizontal flip (2x effective data)
  • Dynamic Dirichlet - Exploration scales with branching factor
  • FPU Reduction - First-play urgency for better MCTS
  • Resign/Draw Adjudication - 30% faster self-play
  • Opening Book - 30 ECO positions for diversity
  • Stratified Sampling - Balanced training data
  • Recency Weighting - Adapt to improving policy
  • KL Regularization - Prevent policy collapse
  • Virtual Loss - Parallel MCTS search
  • Transposition Table - Cache NN evaluations
  • Phase Conditioning - Game phase awareness
  • Tablebase Support - Perfect endgames (Syzygy)

Expected Strength: 2000-2400 Elo (from ~1200 baseline) Total Elo Gain: +600-1160 Elo (conservative) to +850-1560 Elo (optimistic)


🚀 Quick Start

UNC Longleaf Cluster (Recommended - One Command!)

# Optimized for Longleaf's L40 and A100 GPUs
./scripts/submit_longleaf.sh 8 true
#                             ^  ^
#                             |  Use A100 for training
#                             8 L40 actors for self-play

# Timeline: ~11-12 days on 9 GPUs (8 L40 + 1 A100)

Generic SLURM Cluster

sbatch scripts/slurm_full_pipeline_complete.sh \
    data/lichess_db.pgn \
    20000 \
    4

Training Pipeline:

Lichess DB → Teacher Distillation → Supervised → Self-Play + Training → Expert Engine
(20K games)  (Stockfish soft targets) (50K steps)  (2M steps, 10 days)   (2000-2400 Elo)

📚 Complete Documentation

New Users Start Here:

  1. FINAL_SUMMARY.md - Project overview & what's implemented
  2. QUICK_START_IMPROVED.md - Step-by-step training guide
  3. scripts/LONGLEAF_CLUSTER_GUIDE.md - UNC Longleaf specific

Feature Documentation: 4. FEATURES_REFERENCE.md - Quick reference for all 16 features 5. COMPLETE_IMPLEMENTATION_SUMMARY.md - Technical details 6. IMPROVEMENTS_CHANGELOG.md - What's new

SLURM Guide: 7. scripts/SLURM_GUIDE.md - Comprehensive SLURM documentation 8. scripts/README.md - Scripts overview


Total: ~29 days to expert-level engine

See Quick Start Guide for details.


Documentation

Getting Started

Training Pipeline

Operations

Reference


Project Structure

chess-bot/
├── engine/           # Chess rules, MCTS search
│   ├── chesslib.py   # Chess game logic (python-chess wrapper)
│   ├── mcts.py       # Monte Carlo Tree Search
│   └── encode.py     # Board → tensor encoding (115 channels)
│
├── net/              # Neural network
│   ├── model.py      # ResNet24x192 (policy + value heads)
│   └── infer.py      # Inference server (batched GPU inference)
│
├── selfplay/         # Self-play actors
│   ├── actor.py      # MCTS self-play game generator
│   ├── rewards.py    # Shaped reward calculator
│   └── writer.py     # Parquet shard writer
│
├── train/            # Training
│   ├── loop.py       # Training loop (SGD on replay buffer)
│   ├── dataset.py    # Parquet dataset loader
│   └── loss.py       # Policy + value loss
│
├── ops/              # Configuration
│   ├── configs/      # YAML training configs
│   │   ├── train.supervised.yaml      # Supervised pre-training
│   │   └── train.maximum.yaml         # Full 2M step training
│   └── slurm/        # SLURM job scripts
│
├── scripts/          # Automation
│   ├── slurm_full_pipeline.sh         # Complete automated pipeline
│   ├── download_lichess_games.sh      # Get Lichess database
│   ├── convert_pgn_to_training.py     # PGN → Parquet conversion
│   ├── slurm_supervised_pretrain.sh   # Supervised training job
│   └── slurm_train_maximum.sh         # Self-play training job
│
├── docs/             # Documentation (you are here)
└── data/             # Generated data (not in git)
    ├── lichess_pgn/  # Downloaded PGN files (~1TB)
    ├── supervised/   # Converted training data (~5-10GB)
    ├── replay/       # Self-play games (~50-100GB)
    └── models/       # Checkpoints (~500MB each)

Training Phases

Phase 1: Supervised Pre-Training (50K steps, ~6 hours)

Input: 20K Lichess games (Elo 2000+) → 258K positions

What it learns:

  • Castling behavior
  • Piece development
  • Opening principles
  • Basic tactics

Output: Checkpoint at ~1200 Elo

sbatch scripts/slurm_supervised_pretrain.sh

Phase 2: Self-Play Training (2M steps, ~28 days)

Input: Supervised checkpoint + shaped rewards

What it learns:

  • Advanced tactics
  • Positional play
  • Endgame technique
  • Strategic planning

Output: Final model at ~2000+ Elo

sbatch scripts/slurm_train_maximum.sh

Key Features

Supervised Pre-Training

Unlike pure AlphaZero (starts from random), we bootstrap from expert human games:

  • Faster convergence: Learns basics in hours instead of days
  • Better exploration: Starts from diverse openings
  • Higher quality: Avoids learning nonsense moves

Shaped Rewards

Self-play uses shaped rewards to guide learning:

  • Castling bonus: +0.1
  • Development bonus: +0.05
  • Center control: +0.03
  • Repetition penalty: -0.15
  • Tempo penalty: -0.02

Distributed Architecture

  • Inference server: Batched GPU inference (1000+ inferences/sec)
  • Self-play actors: CPU-based MCTS game generation (scale to 100+ actors)
  • Training loop: GPU training on replay buffer
  • Evaluation gate: Automated strength testing

Hardware Requirements

Minimum (Local Testing)

  • GPU: 12GB VRAM (RTX 3080)
  • CPU: 8 cores
  • RAM: 32GB
  • Disk: 100GB SSD

Recommended (Full Training)

  • GPU: 48GB VRAM (L40, A100)
  • CPU: 16+ cores
  • RAM: 64GB
  • Disk: 2TB SSD

Dataset Sizes

  • Lichess PGN: ~1TB (6 months)
  • Supervised data: ~5-10GB (20K games)
  • Self-play replay: ~50-100GB (rotating window)
  • Checkpoints: ~500MB each

Model Architecture

ResNet 24 blocks × 192 width

  • Input: 115 channels × 8×8 board representation
  • Backbone: 24 residual blocks (Conv → BatchNorm → ReLU)
  • Policy head: 2 outputs (from-square, to-square logits)
  • Value head: 1 output (position evaluation)
  • Parameters: ~42M
  • Training: Mixed precision (FP16)

See Model Architecture for details.


Performance

Training Speed (L40 GPU)

  • Supervised: ~270 steps/hour (batch 1024)
  • Self-play: ~120 steps/hour (batch 1024, with self-play overhead)

Self-Play Generation

  • Single actor: ~50 games/hour
  • 10 actors: ~500 games/hour
  • 100 actors: ~5000 games/hour

Strength Progression

Steps Phase Elo Quality
0 Random 400 Random moves
50K Supervised 1200 Beginner chess
200K Early RL 1400 Basic strategy
500K Mid RL 1600 Solid amateur
1M Late RL 1800 Strong amateur
2M Final 2000+ Expert

Requirements

# Core dependencies
python >= 3.10
torch >= 2.2.0
python-chess >= 1.999
pyarrow >= 14.0.0

# SLURM cluster (for distributed training)
# GPU with CUDA 12.x (for training)

# See requirements.txt for full list

Installation

# Clone repo
git clone <your-repo>
cd chess-bot

# Setup environment
bash scripts/setup.sh

# Or manual setup
pip install -r requirements.txt

Local Development

Start all components (local testing):

bash scripts/run_all_local.sh

Or start components individually:

# Terminal 1: Inference server
bash scripts/start_infer_pool.sh

# Terminal 2: Self-play actor
python -m selfplay.actor --actor_id 0

# Terminal 3: Training
python -m train.loop --config ops/configs/train.maximum.yaml

# Terminal 4: Evaluation
python -m train.eval_gate

Testing the Model

Web Interface (Recommended)

Play against your model with an interactive web interface:

# Install web dependencies (one-time)
pip install fastapi uvicorn[standard] websockets python-multipart

# Start server (easy method)
bash scripts/start_web_interface.sh data/models/ckpt_final.pt

# Or manual method
export CHESS_MODEL_PATH=data/models/ckpt_final.pt
uvicorn web.server:app --host 0.0.0.0 --port 8000

# Open browser to http://localhost:8000

Features:

  • Drag-and-drop chess board
  • Play as White or Black
  • Configurable search depth (100-2000 simulations)
  • Real-time MCTS visualization:
    • Live progress bar (updates every 50 simulations)
    • Top move candidates table with visit counts and win rates
    • Search statistics (time, speed)
    • Principal variation display
  • Position evaluation tracking
  • Move history
  • PGN export

Command Line

# Play against the model (terminal)
python scripts/play_game.py data/models/ckpt_02000000.pt

# Evaluate on test positions
python scripts/evaluate_model.py data/models/current.ckpt --test-openings

# Run UCI engine (for chess GUIs)
python -m engine.uci_bot data/models/current.ckpt

Configuration Files

All training configurations in ops/configs/:

  • train.supervised.yaml - Supervised pre-training (50K steps)
  • train.maximum.yaml - Full training to 2M steps
  • train.production.yaml - Production training (1M steps)
  • selfplay.yaml - Self-play actor settings
  • infer.yaml - Inference server settings

See Configuration Reference for details.


SLURM Jobs

All SLURM scripts in scripts/:

# Full pipeline
sbatch scripts/slurm_full_pipeline.sh

# Individual steps
sbatch scripts/slurm_download_lichess.sh     # Step 1: Download
sbatch scripts/slurm_convert_pgn.sh          # Step 2: Convert
sbatch scripts/slurm_supervised_pretrain.sh  # Step 3: Supervised
sbatch scripts/slurm_train_maximum.sh        # Step 4: Self-play

# Monitor
squeue -u $USER
bash scripts/check_training_progress.sh

Monitoring

# Training progress
bash scripts/check_training_progress.sh

# Live logs
tail -f logs/slurm/train_max_*.log

# TensorBoard (if enabled)
tensorboard --logdir data/tb/

Common Workflows

Starting from scratch:

sbatch scripts/slurm_full_pipeline.sh  # Everything automated

Already have Lichess data:

sbatch scripts/slurm_convert_pgn.sh           # Convert
sbatch scripts/slurm_supervised_pretrain.sh   # Train

Already have supervised checkpoint:

sbatch scripts/slurm_train_maximum.sh  # Self-play to 2M

Resume from interruption:

# Training automatically resumes from latest checkpoint
sbatch scripts/slurm_train_maximum.sh

Troubleshooting

See Troubleshooting Guide for common issues:

  • Policy loss is 0.0 → Data format bug (reconvert data)
  • Out of memory → Reduce batch size
  • Training is slow → Check GPU utilization
  • Job stuck in queue → Check SLURM partition

License

MIT License


Acknowledgments

  • AlphaZero paper (Silver et al., 2017)
  • Leela Chess Zero project
  • Lichess.org for open database
  • python-chess library

Contributing

Contributions welcome! Please:

  1. Follow code style (run make fmt)
  2. Add tests for new features
  3. Update documentation
  4. Submit PR with clear description

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