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Jonathan Rahn

jrahn
AI Lab Lead
Drees & Sommer SE
Hamburg, Germany
www.linkedin.com/in/jonrahn
rahnjonathan
jorahn

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Intro

Jonathan Rahn

AI Lab Lead, Drees & Sommer



Research Focus


Exploring transformer-based strategic reasoning through chess as a testbed, demonstrating that language models can develop sophisticated game-playing capabilities without traditional search algorithms. In collaboration with LAION, developing models that challenge fundamental assumptions about how AI systems learn strategic thinking.



Key Projects




🏆 ROOK-CLF-9M - Classification Chess AI


  • 49% action accuracy on ChessBench dataset
  • 57% checkmate-in-one accuracy (BIG-bench)
  • 9M parameter LLaMA-based decoder reproducing Google DeepMind's searchless chess methodology
  • 📊 W&B Report: ROOK-CLF Training - Detailed training metrics and ablations
  • 🎮 Interactive Demo - Try the model in your browser with attention visualization



🧠 RookWorld-LM - Unified Agent+Environment


  • 32.1% checkmate-in-one accuracy (beats ChessGPT-Base 26.5%)
  • 99.9% environment simulation accuracy
  • Single transformer handling both chess policy and world modeling
  • Enables closed-loop self-play without external engines



ROOK-LM - Chain-of-Thought Reasoning


  • 22.2% action accuracy with detailed reasoning traces
  • 24.4% checkmate-in-one accuracy
  • Trained on 40M positions with Stockfish annotations (6B tokens)



Technical Contributions



  • Novel Architectures: Unified world modeling in transformers
  • Strategic Tokenization: Custom FEN representations for consistent attention patterns
  • Dataset Engineering: 40M+ positions with Stockfish annotations on supercomputing infrastructure
  • Open Science: All models, datasets, and code publicly available



Research Impact


Published at LAION Research Notes with collaborators from LAION/JSC and Tokyo Tech/Sakana AI. Contributing to democratization of strategic AI research through open models and reproducible methodologies.

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Exploring how language models can learn strategic thinking through next-token prediction on appropriately structured data.
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