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A default assumption in the design of reinforcement-learning algorithms is that a decision-making agent always explores to learn optimal behavior. In sufficiently complex environments that approach the vastness and scale of the real world,…

Machine Learning · Computer Science 2024-07-23 Dilip Arumugam , Saurabh Kumar , Ramki Gummadi , Benjamin Van Roy

Exploration remains a fundamental challenge in reinforcement learning (RL), particularly in environments with sparse or adversarial reward structures. In this work, we study how the architecture of deep neural policies implicitly shapes…

Machine Learning · Computer Science 2025-07-28 Jacob Adamczyk

Large scale reinforcement learning has become a central tool for improving reasoning in large language models. At this scale, generation is often lagged or asynchronous, so updates are performed on data collected by older policies. This…

Machine Learning · Computer Science 2026-05-28 Otmane Sakhi , Aleksei Arzhantsev , Imad Aouali , Flavian Vasile

Large language models exhibit systematic vulnerabilities to adversarial attacks despite extensive safety alignment. We provide a mechanistic analysis revealing that position-dependent gradient weakening during autoregressive training…

Machine Learning · Computer Science 2025-11-18 Thong Bach , Dung Nguyen , Thao Minh Le , Truyen Tran

Deep networks have achieved impressive results across a variety of important tasks. However a known weakness is a failure to perform well when evaluated on data which differ from the training distribution, even if these differences are very…

While offline reinforcement learning provides reliable policies for real-world deployment, its inherent pessimism severely restricts an agent's ability to explore and collect novel data online. Drawing inspiration from safe reinforcement…

Machine Learning · Computer Science 2026-03-20 Amirhossein Roknilamouki , Arnob Ghosh , Eylem Ekici , Ness B. Shroff

We study offline reinforcement learning (RL) which seeks to learn a good policy based on a fixed, pre-collected dataset. A fundamental challenge behind this task is the distributional shift due to the dataset lacking sufficient exploration,…

Machine Learning · Computer Science 2023-10-11 Wenzhuo Zhou

The demand for more transparency of decision-making processes of deep reinforcement learning agents is greater than ever, due to their increased use in safety critical and ethically challenging domains such as autonomous driving. In this…

Machine Learning · Computer Science 2020-04-08 Richard Meyes , Moritz Schneider , Tobias Meisen

With reinforcement learning, an agent could learn complex behaviors from high-level abstractions of the task. However, exploration and reward shaping remained challenging for existing methods, especially in scenarios where the extrinsic…

Machine Learning · Computer Science 2020-06-11 Jie Chen , Wenjun Xu

Most model-free reinforcement learning methods leverage state representations (embeddings) for generalization, but either ignore structure in the space of actions or assume the structure is provided a priori. We show how a policy can be…

Machine Learning · Computer Science 2019-05-16 Yash Chandak , Georgios Theocharous , James Kostas , Scott Jordan , Philip S. Thomas

We focus on parameterized policy search for reinforcement learning over continuous action spaces. Typically, one assumes the score function associated with a policy is bounded, which fails to hold even for Gaussian policies. To properly…

Machine Learning · Computer Science 2022-02-01 Amrit Singh Bedi , Souradip Chakraborty , Anjaly Parayil , Brian Sadler , Pratap Tokekar , Alec Koppel

What is a good exploration strategy for an agent that interacts with an environment in the absence of external rewards? Ideally, we would like to get a policy driving towards a uniform state-action visitation (highly exploring) in a minimum…

Machine Learning · Computer Science 2019-12-20 Mirco Mutti , Marcello Restelli

Multi-agent control problems constitute an interesting area of application for deep reinforcement learning models with continuous action spaces. Such real-world applications, however, typically come with critical safety constraints that…

Machine Learning · Computer Science 2021-08-12 Ziyad Sheebaelhamd , Konstantinos Zisis , Athina Nisioti , Dimitris Gkouletsos , Dario Pavllo , Jonas Kohler

We propose a framework for ensuring safe behavior of a reinforcement learning agent when the reward function may be difficult to specify. In order to do this, we rely on the existence of demonstrations from expert policies, and we provide a…

Machine Learning · Computer Science 2018-11-22 Jessie Huang , Fa Wu , Doina Precup , Yang Cai

Policy-based reinforcement learning methods suffer from the policy collapse problem. We find valued-based reinforcement learning methods with {\epsilon}-greedy mechanism are capable of enjoying three characteristics, Closed-form Diversity,…

Machine Learning · Computer Science 2021-06-03 Changnan Xiao , Haosen Shi , Jiajun Fan , Shihong Deng

Existing imitation learning approaches often require that the complete demonstration data, including sequences of actions and states, are available. In this paper, we consider a more realistic and difficult scenario where a reinforcement…

Machine Learning · Computer Science 2019-03-12 Xiaoxiao Guo , Shiyu Chang , Mo Yu , Gerald Tesauro , Murray Campbell

Policy gradient methods are notorious for having a large variance and high sample complexity. To mitigate this, we introduce SoftTreeMax -- a generalization of softmax that employs planning. In SoftTreeMax, we extend the traditional logits…

Machine Learning · Computer Science 2025-05-27 Gal Dalal , Assaf Hallak , Gugan Thoppe , Shie Mannor , Gal Chechik

Deep Reinforcement Learning (DRL) is widely recognized as sample-inefficient, a limitation attributable in part to the high dimensionality and substantial functional redundancy inherent to the policy parameter space. A recent framework,…

Machine Learning · Computer Science 2026-04-03 Andrea Fraschini , Davide Tenedini , Riccardo Zamboni , Mirco Mutti , Marcello Restelli

Deep reinforcement learning (RL) excels in various control tasks, yet the absence of safety guarantees hampers its real-world applicability. In particular, explorations during learning usually results in safety violations, while the RL…

Robotics · Computer Science 2025-06-04 Yifan Sun , Feihan Li , Weiye Zhao , Rui Chen , Tianhao Wei , Changliu Liu

Natural policy gradient (NPG) methods with entropy regularization achieve impressive empirical success in reinforcement learning problems with large state-action spaces. However, their convergence properties and the impact of entropy…

Machine Learning · Computer Science 2026-02-17 Semih Cayci , Niao He , R. Srikant