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Optimization of parameterized policies for reinforcement learning (RL) is an important and challenging problem in artificial intelligence. Among the most common approaches are algorithms based on gradient ascent of a score function…

Machine Learning · Computer Science 2020-06-15 Sriram Srinivasan , Marc Lanctot , Vinicius Zambaldi , Julien Perolat , Karl Tuyls , Remi Munos , Michael Bowling

In this paper, we propose a novel policy iteration method, called dynamic policy programming (DPP), to estimate the optimal policy in the infinite-horizon Markov decision processes. We prove the finite-iteration and asymptotic l\infty-norm…

Machine Learning · Computer Science 2011-09-09 Mohammad Gheshlaghi Azar , Vicenc Gomez , Hilbert J. Kappen

A core challenge in policy optimization in competitive Markov decision processes is the design of efficient optimization methods with desirable convergence and stability properties. To tackle this, we propose competitive policy optimization…

Machine Learning · Computer Science 2020-06-19 Manish Prajapat , Kamyar Azizzadenesheli , Alexander Liniger , Yisong Yue , Anima Anandkumar

This paper investigates trajectory tracking problem for a class of underactuated autonomous underwater vehicles (AUVs) with unknown dynamics and constrained inputs. Different from existing policy gradient methods which employ single…

Machine Learning · Computer Science 2019-09-10 Wenjie Shi , Shiji Song , Cheng Wu , C. L. Philip Chen

Demonstrations are an effective alternative to task specification for learning agents in settings where designing a reward function is difficult. However, demonstrating expert behavior in the action space of the agent becomes unwieldy when…

Machine Learning · Computer Science 2024-09-23 Harshit Sikchi , Caleb Chuck , Amy Zhang , Scott Niekum

Policy evaluation estimates the performance of a policy by (1) collecting data from the environment and (2) processing raw data into a meaningful estimate. Due to the sequential nature of reinforcement learning, any improper data-collecting…

Machine Learning · Computer Science 2025-03-21 Shuze Daniel Liu , Claire Chen , Shangtong Zhang

Direct Preference Optimization (DPO) optimizes language models to align with human preferences. Utilizing on-policy samples, generated directly by the policy model, typically results in better performance due to its distribution consistency…

Machine Learning · Computer Science 2025-03-21 Yunan Wang , Jijie Li , Bo-Wen Zhang , Liangdong Wang , Guang Liu

In this paper, we discuss the deterministic policy gradient using the Actor-Critic methods based on the linear compatible advantage function approximator, where the input spaces are continuous. When the policy is restricted by hard…

Systems and Control · Electrical Eng. & Systems 2021-04-07 Arash Bahari Kordabad , Hossein Nejatbakhsh Esfahani , Sebastien Gros

Policy gradient algorithms typically combine discounted future rewards with an estimated value function, to compute the direction and magnitude of parameter updates. However, for most Reinforcement Learning tasks, humans can provide…

Machine Learning · Computer Science 2019-04-09 Ishan Durugkar , Matthew Hausknecht , Adith Swaminathan , Patrick MacAlpine

As large language model agents tackle increasingly complex long-horizon tasks, effective post-training becomes critical. Prior work faces fundamental challenges: outcome-only rewards fail to precisely attribute credit to intermediate steps,…

Computation and Language · Computer Science 2026-04-30 Mukai Li , Qingcheng Zeng , Tianqing Fang , Zhenwen Liang , Linfeng Song , Qi Liu , Haitao Mi , Dong Yu

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…

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

We study a sequential decision-making problem for a profit-maximizing operator of an autonomous mobility-on-demand system. Optimizing a central operator's vehicle-to-request dispatching policy requires efficient and effective fleet control…

Systems and Control · Electrical Eng. & Systems 2025-06-24 Zeno Woywood , Jasper I. Wiltfang , Julius Luy , Tobias Enders , Maximilian Schiffer

Most real-world optimization problems have multiple objectives. A system designer needs to find a policy that trades off these objectives to reach a desired operating point. This problem has been studied extensively in the setting of known…

Machine Learning · Computer Science 2022-01-26 Nan Wang , Hongning Wang , Maryam Karimzadehgan , Branislav Kveton , Craig Boutilier

We study a new two-time-scale stochastic gradient method for solving optimization problems, where the gradients are computed with the aid of an auxiliary variable under samples generated by time-varying MDPs controlled by the underlying…

Optimization and Control · Mathematics 2024-08-27 Sihan Zeng , Thinh T. Doan , Justin Romberg

Adversarial optimization algorithms that explicitly search for flaws in agents' policies have been successfully applied to finding robust and diverse policies in multi-agent settings. However, the success of adversarial optimization has…

Artificial Intelligence · Computer Science 2025-11-13 Niklas Lauffer , Ameesh Shah , Micah Carroll , Sanjit A. Seshia , Stuart Russell , Michael Dennis

The famous Policy Iteration algorithm alternates between policy improvement and policy evaluation. Implementations of this algorithm with several variants of the latter evaluation stage, e.g, $n$-step and trace-based returns, have been…

Artificial Intelligence · Computer Science 2018-08-01 Yonathan Efroni , Gal Dalal , Bruno Scherrer , Shie Mannor

This paper introduces a novel causal framework for multi-stage decision-making in natural language action spaces where outcomes are only observed after a sequence of actions. While recent approaches like Proximal Policy Optimization (PPO)…

Computation and Language · Computer Science 2025-02-26 Bohan Zhang , Yixin Wang , Paramveer S. Dhillon

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

Multi-step greedy policies have been extensively used in model-based reinforcement learning (RL), both when a model of the environment is available (e.g.,~in the game of Go) and when it is learned. In this paper, we explore their benefits…

Machine Learning · Computer Science 2020-07-14 Manan Tomar , Yonathan Efroni , Mohammad Ghavamzadeh