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We propose an actor-critic framework to solve the time-continuous stochastic optimal control problem. A least square temporal difference method is applied to compute the value function for the critic. The policy gradient method is…

Optimization and Control · Mathematics 2025-01-27 Mo Zhou , Jianfeng Lu

Cooperative multi-agent systems can be naturally used to model many real world problems, such as network packet routing and the coordination of autonomous vehicles. There is a great need for new reinforcement learning methods that can…

Artificial Intelligence · Computer Science 2024-12-12 Jakob Foerster , Gregory Farquhar , Triantafyllos Afouras , Nantas Nardelli , Shimon Whiteson

Soft Actor-Critic (SAC) is considered the state-of-the-art algorithm in continuous action space settings. It uses the maximum entropy framework for efficiency and stability, and applies a heuristic temperature Lagrange term to tune the…

Machine Learning · Computer Science 2021-12-07 Yaosheng Xu , Dailin Hu , Litian Liang , Stephen McAleer , Pieter Abbeel , Roy Fox

Continuous-time stochastic control with time-inhomogeneous jump-diffusion dynamics is central in finance and economics, but computing optimal policies is difficult under explicit time dependence, discontinuous shocks, and high…

Optimization and Control · Mathematics 2026-04-08 Liya Guo , Ruimeng Hu , Xu Yang , Yi Zhu

Soft actor-critic (SAC) is a popular algorithm for max-entropy reinforcement learning. In practice, the energy-based policies in SAC are often approximated using simple policy classes for efficiency, sacrificing the expressiveness and…

Machine Learning · Computer Science 2026-01-01 Yuyang Zhang , Yang Hu , Bo Dai , Na Li

In this paper, we propose a distributed off-policy actor critic method to solve multi-agent reinforcement learning problems. Specifically, we assume that all agents keep local estimates of the global optimal policy parameter and update…

Machine Learning · Computer Science 2019-03-25 Yan Zhang , Michael M. Zavlanos

The actor-critic (AC) framework has achieved strong empirical success in off-policy reinforcement learning but suffers from the "moving target" problem, where the evaluated policy changes continually. Functional critics, or…

Machine Learning · Computer Science 2026-02-10 Qinxun Bai , Yuxuan Han , Wei Xu , Zhengyuan Zhou

Actor-critic methods are widely used in offline reinforcement learning practice, but are not so well-understood theoretically. We propose a new offline actor-critic algorithm that naturally incorporates the pessimism principle, leading to…

Machine Learning · Computer Science 2021-08-20 Andrea Zanette , Martin J. Wainwright , Emma Brunskill

As an important type of reinforcement learning algorithms, actor-critic (AC) and natural actor-critic (NAC) algorithms are often executed in two ways for finding optimal policies. In the first nested-loop design, actor's one update of…

Machine Learning · Computer Science 2020-05-11 Tengyu Xu , Zhe Wang , Yingbin Liang

Policy gradient methods are reinforcement learning algorithms that adapt a parameterized policy by following a performance gradient estimate. Conventional policy gradient methods use Monte-Carlo techniques to estimate the gradient, which…

Machine Learning · Computer Science 2026-05-01 Mohammad Ghavamzadeh , Yaakov Engel , Michal Valko

We study policy gradient for mean-field control in continuous time in a reinforcement learning setting. By considering randomised policies with entropy regularisation, we derive a gradient expectation representation of the value function,…

Machine Learning · Statistics 2023-03-14 Noufel Frikha , Maximilien Germain , Mathieu Laurière , Huyên Pham , Xuanye Song

Soft actor-critic (SAC) in reinforcement learning is expected to be one of the next-generation robot control schemes. Its ability to maximize policy entropy would make a robotic controller robust to noise and perturbation, which is useful…

Machine Learning · Computer Science 2023-07-04 Taisuke Kobayashi

In this paper, we propose an actor ensemble algorithm, named ACE, for continuous control with a deterministic policy in reinforcement learning. In ACE, we use actor ensemble (i.e., multiple actors) to search the global maxima of the critic.…

Machine Learning · Computer Science 2018-11-12 Shangtong Zhang , Hao Chen , Hengshuai Yao

In multi-agent reinforcement learning, multiple agents learn simultaneously while interacting with a common environment and each other. Since the agents adapt their policies during learning, not only the behavior of a single agent becomes…

Artificial Intelligence · Computer Science 2022-04-13 Yuan Tian , Klaus-Rudolf Kladny , Qin Wang , Zhiwu Huang , Olga Fink

Reinforcement learning (RL) has substantially improved the ability of large language model (LLM) agents to interact with environments and solve multi-turn tasks. However, effective agentic RL remains challenging: sparse outcome-only rewards…

Recent advances in deep reinforcement learning have achieved impressive results in a wide range of complex tasks, but poor sample efficiency remains a major obstacle to real-world deployment. Soft actor-critic (SAC) mitigates this problem…

Machine Learning · Computer Science 2024-09-10 Luca Della Libera

While Soft Actor-Critic (SAC) is highly effective in continuous control, its discrete counterpart (DSAC) performs poorly on challenging discrete-action domains such as Atari. Consequently, starting from DSAC, we revisit the design of…

Machine Learning · Computer Science 2026-05-13 Reza Asad , Reza Babanezhad , Sharan Vaswani

We consider the estimation of the policy gradient in partially observable Markov decision processes (POMDP) with a special class of structured policies that are finite-state controllers. We show that the gradient estimation can be done in…

Machine Learning · Computer Science 2012-07-09 Huizhen Yu

Current state-of-the-art model-based reinforcement learning algorithms use trajectory sampling methods, such as the Cross-Entropy Method (CEM), for planning in continuous control settings. These zeroth-order optimizers require sampling a…

Machine Learning · Computer Science 2021-12-16 Kevin Huang , Sahin Lale , Ugo Rosolia , Yuanyuan Shi , Anima Anandkumar

The exploration mechanism used by a Deep Reinforcement Learning (RL) agent plays a key role in determining its sample efficiency. Thus, improving over random exploration is crucial to solve long-horizon tasks with sparse rewards. We propose…

Machine Learning · Computer Science 2019-12-17 Andrey Kurenkov , Ajay Mandlekar , Roberto Martin-Martin , Silvio Savarese , Animesh Garg