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Actor-critic (AC) algorithms, empowered by neural networks, have had significant empirical success in recent years. However, most of the existing theoretical support for AC algorithms focuses on the case of linear function approximations,…

Machine Learning · Computer Science 2024-04-02 Yufeng Zhang , Siyu Chen , Zhuoran Yang , Michael I. Jordan , Zhaoran Wang

Actor-critic algorithms have shown remarkable success in solving state-of-the-art decision-making problems. However, despite their empirical effectiveness, their theoretical underpinnings remain relatively unexplored, especially with neural…

Machine Learning · Computer Science 2023-06-21 Mudit Gaur , Amrit Singh Bedi , Di Wang , Vaneet Aggarwal

We consider an improper reinforcement learning setting where a learner is given $M$ base controllers for an unknown Markov decision process, and wishes to combine them optimally to produce a potentially new controller that can outperform…

Machine Learning · Computer Science 2022-07-20 Mohammadi Zaki , Avinash Mohan , Aditya Gopalan , Shie Mannor

In this work, we consider policy-based methods for solving the reinforcement learning problem, and establish the sample complexity guarantees. A policy-based algorithm typically consists of an actor and a critic. We consider using various…

Machine Learning · Computer Science 2023-01-16 Zaiwei Chen , Siva Theja Maguluri

The actor-critic (AC) reinforcement learning algorithms have been the powerhouse behind many challenging applications. Nevertheless, its convergence is fragile in general. To study its instability, existing works mostly consider the…

Machine Learning · Computer Science 2023-02-28 Xuyang Chen , Jingliang Duan , Yingbin Liang , Lin Zhao

Asynchronous and parallel implementation of standard reinforcement learning (RL) algorithms is a key enabler of the tremendous success of modern RL. Among many asynchronous RL algorithms, arguably the most popular and effective one is the…

Machine Learning · Computer Science 2023-08-02 Han Shen , Kaiqing Zhang , Mingyi Hong , Tianyi Chen

Actor-Critic methods are widely used for their scalability, yet existing theoretical guarantees for infinite-horizon average-reward Markov Decision Processes (MDPs) often rely on restrictive ergodicity assumptions. We propose NAC-B, a…

Machine Learning · Computer Science 2025-10-28 Swetha Ganesh , Vaneet Aggarwal

Actor-critic methods, a type of model-free Reinforcement Learning, have been successfully applied to challenging tasks in continuous control, often achieving state-of-the art performance. However, wide-scale adoption of these methods in…

Machine Learning · Statistics 2019-10-29 Kamil Ciosek , Quan Vuong , Robert Loftin , Katja Hofmann

Actor-critic (AC) methods are ubiquitous in reinforcement learning. Although it is understood that AC methods are closely related to policy gradient (PG), their precise connection has not been fully characterized previously. In this paper,…

Artificial Intelligence · Computer Science 2021-06-15 Junfeng Wen , Saurabh Kumar , Ramki Gummadi , Dale Schuurmans

Actor-critic algorithms address the dual goals of reinforcement learning (RL), policy evaluation and improvement via two separate function approximators. The practicality of this approach comes at the expense of training instability, caused…

Machine Learning · Computer Science 2024-06-11 Bahareh Tasdighi , Abdullah Akgül , Manuel Haussmann , Kenny Kazimirzak Brink , Melih Kandemir

Soft Actor-Critic (SAC) is an off-policy actor-critic reinforcement learning algorithm, essentially based on entropy regularization. SAC trains a policy by maximizing the trade-off between expected return and entropy (randomness in the…

Machine Learning · Computer Science 2021-09-27 Chayan Banerjee , Zhiyong Chen , Nasimul Noman

Many popular practical reinforcement learning (RL) algorithms employ evolving reward functions-through techniques such as reward shaping, entropy regularization, or curriculum learning-yet their theoretical foundations remain…

Machine Learning · Computer Science 2025-10-15 Rui Hu , Yu Chen , Longbo Huang

In this paper, we establish last-iterate convergence rates for off-policy actor--critic methods in reinforcement learning. In particular, under a single-loop, single-timescale implementation and a broad class of policy updates, including…

Machine Learning · Computer Science 2026-05-14 Ishaq Hamza , Zaiwei Chen

We focus on a simulation-based optimization problem of choosing the best design from the feasible space. Although the simulation model can be queried with finite samples, its internal processing rule cannot be utilized in the optimization…

Machine Learning · Computer Science 2021-11-02 Kuo Li , Qing-Shan Jia , Jiaqi Yan

In cooperative stochastic games multiple agents work towards learning joint optimal actions in an unknown environment to achieve a common goal. In many real-world applications, however, constraints are often imposed on the actions that can…

Multiagent Systems · Computer Science 2020-07-14 Raghuram Bharadwaj Diddigi , Sai Koti Reddy Danda , Prabuchandran K. J. , Shalabh Bhatnagar

In this paper, sample-aware policy entropy regularization is proposed to enhance the conventional policy entropy regularization for better exploration. Exploiting the sample distribution obtainable from the replay buffer, the proposed…

Machine Learning · Computer Science 2021-06-10 Seungyul Han , Youngchul Sung

The two-time scale nature of SAC, which is an actor-critic algorithm, is characterised by the fact that the critic estimate has not converged for the actor at any given time, but since the critic learns faster than the actor, it ensures…

We present the first class of policy-gradient algorithms that work with both state-value and policy function-approximation, and are guaranteed to converge under off-policy training. Our solution targets problems in reinforcement learning…

Artificial Intelligence · Computer Science 2018-02-23 Hamid Reza Maei

We investigate the neural Actor Critic algorithm using shallow neural networks for both the Actor and Critic models. The focus of this work is twofold: first, to compare the convergence properties of the network outputs under various…

Machine Learning · Computer Science 2026-01-27 Nikos Georgoudios , Konstantinos Spiliopoulos , Justin Sirignano

By using an parametric value function to replace the Monte-Carlo rollouts for value estimation, the actor-critic (AC) algorithms can reduce the variance of stochastic policy gradient so that to improve the convergence rate. While existing…

Machine Learning · Computer Science 2024-08-19 Yanjie Dong , Haijun Zhang , Gang Wang , Shisheng Cui , Xiping Hu