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High-precision control tasks present substantial challenges for reinforcement learning (RL) algorithms, frequently resulting in suboptimal performance attributed to network approximation inaccuracies and inadequate sample quality.These…

Machine Learning · Computer Science 2025-02-05 Donghe Chen , Yubin Peng , Tengjie Zheng , Han Wang , Chaoran Qu , Lin Cheng

Policy gradient methods are widely used for control in reinforcement learning, particularly for the continuous action setting. There have been a host of theoretically sound algorithms proposed for the on-policy setting, due to the existence…

Machine Learning · Computer Science 2019-06-21 Ehsan Imani , Eric Graves , Martha White

We prove under commonly used assumptions the convergence of actor-critic reinforcement learning algorithms, which simultaneously learn a policy function, the actor, and a value function, the critic. Both functions can be deep neural…

Machine Learning · Computer Science 2020-12-03 Markus Holzleitner , Lukas Gruber , José Arjona-Medina , Johannes Brandstetter , Sepp Hochreiter

We propose Adversarially Trained Actor Critic (ATAC), a new model-free algorithm for offline reinforcement learning (RL) under insufficient data coverage, based on the concept of relative pessimism. ATAC is designed as a two-player…

Machine Learning · Computer Science 2022-07-07 Ching-An Cheng , Tengyang Xie , Nan Jiang , Alekh Agarwal

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

Background: Deep Deterministic Policy Gradient-based reinforcement learning algorithms utilize Actor-Critic architectures, where both networks are typically trained using identical batches of replayed transitions. However, the learning…

Machine Learning · Computer Science 2025-12-08 Mehmet Efe Lorasdagi , Dogan Can Cicek , Furkan Burak Mutlu , Suleyman Serdar Kozat

Reinforcement learning in multi-agent scenarios is important for real-world applications but presents challenges beyond those seen in single-agent settings. We present an actor-critic algorithm that trains decentralized policies in…

Machine Learning · Computer Science 2019-05-29 Shariq Iqbal , Fei Sha

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

We revisit the standard formulation of tabular actor-critic algorithm as a two time-scale stochastic approximation with value function computed on a faster time-scale and policy computed on a slower time-scale. This emulates policy…

Machine Learning · Computer Science 2024-06-21 Shalabh Bhatnagar , Vivek S. Borkar , Soumyajit Guin

We reformulate the option framework as two parallel augmented MDPs. Under this novel formulation, all policy optimization algorithms can be used off the shelf to learn intra-option policies, option termination conditions, and a master…

Machine Learning · Computer Science 2019-09-12 Shangtong Zhang , Shimon Whiteson

In this paper, a new offline actor-critic learning algorithm is introduced: Sampled Policy Gradient (SPG). SPG samples in the action space to calculate an approximated policy gradient by using the critic to evaluate the samples. This…

Artificial Intelligence · Computer Science 2018-09-18 Anton Orell Wiehe , Nil Stolt Ansó , Madalina M. Drugan , Marco A. Wiering

To learn approximately optimal acting policies for decision problems, modern Actor Critic algorithms rely on deep Neural Networks (DNNs) to parameterize the acting policy and greedification operators to iteratively improve it. The reliance…

In this work, we propose Behavior-Guided Actor-Critic (BAC), an off-policy actor-critic deep RL algorithm. BAC mathematically formulates the behavior of the policy through autoencoders by providing an accurate estimation of how frequently…

Machine Learning · Computer Science 2021-04-12 Ammar Fayad , Majd Ibrahim

We study policy optimization in Stackelberg mean field games (MFGs), a hierarchical framework for modeling the strategic interaction between a single leader and an infinitely large population of homogeneous followers. The objective can be…

Machine Learning · Computer Science 2025-11-27 Sihan Zeng , Benjamin Patrick Evans , Sujay Bhatt , Leo Ardon , Sumitra Ganesh , Alec Koppel

We present temporally abstract actor-critic (TAAC), a simple but effective off-policy RL algorithm that incorporates closed-loop temporal abstraction into the actor-critic framework. TAAC adds a second-stage binary policy to choose between…

Machine Learning · Computer Science 2021-10-13 Haonan Yu , Wei Xu , Haichao Zhang

The Sampled Policy Gradient (SPG) algorithm is a new offline actor-critic variant that samples in the action space to approximate the policy gradient. It does so by using the critic to evaluate the sampled actions. SPG offers theoretical…

Machine Learning · Computer Science 2019-10-10 Nil Stolt Ansó

Actor-critic methods can achieve incredible performance on difficult reinforcement learning problems, but they are also prone to instability. This is partly due to the interaction between the actor and critic during learning, e.g., an…

Machine Learning · Computer Science 2019-02-26 Simone Parisi , Voot Tangkaratt , Jan Peters , Mohammad Emtiyaz Khan

Actor-critic (AC) algorithms are a class of model-free deep reinforcement learning algorithms, which have proven their efficacy in diverse domains, especially in solving continuous control problems. Improvement of exploration (action…

Machine Learning · Computer Science 2022-10-04 Chayan Banerjee , Zhiyong Chen , Nasimul Noman

Policy gradient is an efficient technique for improving a policy in a reinforcement learning setting. However, vanilla online variants are on-policy only and not able to take advantage of off-policy data. In this paper we describe a new…

Machine Learning · Computer Science 2017-04-10 Brendan O'Donoghue , Remi Munos , Koray Kavukcuoglu , Volodymyr Mnih

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