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Mattie Fellows

6 accepted papers

2026

Evolution Strategies at the Hyperscale

ICML 2026poster

Evolution Strategies (ES) is a class of powerful black-box optimisation methods that are highly parallelisable and can handle non-differentiable and noisy objectives. However, naïve ES becomes prohibitively expensive at scale on GPUs due to the low arithmetic intensity of batched matrix multiplicati…

Cited by 0SourceScholar
2025

Simplifying Deep Temporal Difference Learning

ICLR 2025spotlight

$Q$-learning played a foundational role in the field reinforcement learning (RL). However, TD algorithms with off-policy data, such as $Q$-learning, or nonlinear function approximation like deep neural networks require several additional tricks to stabilise training, primarily a large replay buffer…

2024

Adam on Local Time: Addressing Nonstationarity in RL with Relative Adam Timesteps

NeurIPS 2024poster

In reinforcement learning (RL), it is common to apply techniques used broadly in machine learning such as neural network function approximators and momentum-based optimizers. However, such tools were largely developed for supervised learning rather than nonstationary RL, leading practitioners to ad…

Cited by 0SourcePDFScholar
2024

Bayesian Exploration Networks

ICML 2024poster

Bayesian reinforcement learning (RL) offers a principled and elegant approach for sequential decision making under uncertainty. Most notably, Bayesian agents do not face an exploration/exploitation dilemma, a major pathology of frequentist methods. However theoretical understanding of model-free app…

Cited by 3SourcePDFScholar
2024

Refining Minimax Regret for Unsupervised Environment Design

ICML 2024poster

In unsupervised environment design, reinforcement learning agents are trained on environment configurations (levels) generated by an adversary that maximises some objective. Regret is a commonly used objective that theoretically results in a minimax regret (MMR) policy with desirable robustness guar…