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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

Off-policy Actor-Critic algorithms have demonstrated phenomenal experimental performance but still require better explanations. To this end, we show its policy evaluation error on the distribution of transitions decomposes into: a Bellman…

Machine Learning · Computer Science 2021-10-07 Ting-Han Fan , Peter J. Ramadge

Although actor-critic methods have been successful in practice, their theoretical analyses have several limitations. Specifically, existing theoretical work either sidesteps the exploration problem by making strong assumptions or analyzes…

Machine Learning · Computer Science 2026-04-02 Max Qiushi Lin , Reza Asad , Kevin Tan , Haque Ishfaq , Csaba Szepesvari , Sharan Vaswani

Actor-critic (AC) methods have exhibited great empirical success compared with other reinforcement learning algorithms, where the actor uses the policy gradient to improve the learning policy and the critic uses temporal difference learning…

Machine Learning · Computer Science 2022-10-11 Yue Wu , Weitong Zhang , Pan Xu , Quanquan Gu

We present a non-asymptotic convergence analysis of $Q$-learning and actor-critic algorithms for robust average-reward Markov Decision Processes (MDPs) under contamination, total-variation (TV) distance, and Wasserstein uncertainty sets. A…

Machine Learning · Computer Science 2025-12-11 Yang Xu , Swetha Ganesh , Vaneet Aggarwal

In recent years, deep off-policy actor-critic algorithms have become a dominant approach to reinforcement learning for continuous control. One of the primary drivers of this improved performance is the use of pessimistic value updates to…

Machine Learning · Computer Science 2022-04-07 Ted Moskovitz , Jack Parker-Holder , Aldo Pacchiano , Michael Arbel , Michael I. Jordan

Despite the empirical success of the actor-critic algorithm, its theoretical understanding lags behind. In a broader context, actor-critic can be viewed as an online alternating update algorithm for bilevel optimization, whose convergence…

Machine Learning · Computer Science 2019-07-16 Zhuoran Yang , Yongxin Chen , Mingyi Hong , Zhaoran Wang

Offline reinforcement learning (RL), also known as batch RL, offers the prospect of policy optimization from large pre-recorded datasets without online environment interaction. It addresses challenges with regard to the cost of data…

We study the robustness of deep reinforcement learning algorithms against distribution shifts within contextual multi-stage stochastic combinatorial optimization problems from the operations research domain. In this context, risk-sensitive…

Machine Learning · Computer Science 2024-02-16 Tobias Enders , James Harrison , Maximilian Schiffer

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

We show that offline actor-critic reinforcement learning can scale to large models - such as transformers - and follows similar scaling laws as supervised learning. We find that offline actor-critic algorithms can outperform strong,…

Actor-Critic models are a class of model-free deep reinforcement learning (RL) algorithms that have demonstrated effectiveness across various robot learning tasks. While considerable research has focused on improving training stability and…

Robotics · Computer Science 2025-10-01 Hanlan Yang , Itamar Mishani , Luca Pivetti , Zachary Kingston , Maxim Likhachev

Off-policy reinforcement learning (RL) has achieved notable success in tackling many complex real-world tasks, by leveraging previously collected data for policy learning. However, most existing off-policy RL algorithms fail to maximally…

Machine Learning · Computer Science 2024-05-30 Yu Luo , Tianying Ji , Fuchun Sun , Jianwei Zhang , Huazhe Xu , Xianyuan Zhan

Off-Policy Actor-Critic (Off-PAC) methods have proven successful in a variety of continuous control tasks. Normally, the critic's action-value function is updated using temporal-difference, and the critic in turn provides a loss for the…

Machine Learning · Computer Science 2020-11-03 Wei Zhou , Yiying Li , Yongxin Yang , Huaimin Wang , Timothy M. Hospedales

Actor-critic algorithms learn an explicit policy (actor), and an accompanying value function (critic). The actor performs actions in the environment, while the critic evaluates the actor's current policy. However, despite their stability…

Artificial Intelligence · Computer Science 2019-02-08 Hélène Plisnier , Denis Steckelmacher , Diederik M. Roijers , Ann Nowé

Model-free off-policy actor-critic methods are an efficient solution to complex continuous control tasks. However, these algorithms rely on a number of design tricks and hyperparameters, making their application to new domains difficult and…

Machine Learning · Computer Science 2021-10-26 Jake Grigsby , Jin Yong Yoo , Yanjun Qi

Offline reinforcement learning (RL) is a promising approach for many control applications but faces challenges such as limited data coverage and value function overestimation. In this paper, we propose an implicit actor-critic (iAC)…

Machine Learning · Computer Science 2024-08-29 Vanshaj Khattar , Ming Jin

Actor-critic methods, a type of model-free reinforcement learning (RL), have achieved state-of-the-art performances in many real-world domains in continuous control. Despite their success, the wide-scale deployment of these models is still…

Machine Learning · Computer Science 2020-12-14 Srinjoy Roy , Saptam Bakshi , Tamal Maharaj

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

The dataset distributions in offline reinforcement learning (RL) often exhibit complex and multi-modal distributions, necessitating expressive policies to capture such distributions beyond widely-used Gaussian policies. To handle such…

Machine Learning · Computer Science 2026-02-23 Jongseong Chae , Jongeui Park , Yongjae Shin , Gyeongmin Kim , Seungyul Han , Youngchul Sung