Hadamax Encoding: Elevating Performance in Model-Free Atari

Neural network architectures have a large impact in machine learning. In reinforcement learning, network architectures have remained notably simple, as changes often lead to small gains in performance. This work introduces a novel encoder architecture for pixel-based model-free reinforcement learning. The Hadamax (\textbf{Hada}mard \textbf{max}-pooling) encoder achieves state-of-the-art performance by max-pooling Hadamard products between GELU-activated parallel hidden layers. Based on the recent PQN algorithm, the Hadamax encoder achieves state-of-the-art model-free performance in the Atari-57 benchmark. Specifically, without applying any algorithmic hyperparameter modifications, Hadamax-PQN achieves an 80\% performance gain over vanilla PQN and significantly surpasses Rainbow-DQN. For reproducibility, the full code is available on \href{this https URL}{GitHub}.

@article{kooi2025_2505.15345,
  title={ Hadamax Encoding: Elevating Performance in Model-Free Atari },
  author={ Jacob E. Kooi and Zhao Yang and Vincent François-Lavet },
  journal={arXiv preprint arXiv:2505.15345},
  year={ 2025 }
}