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We propose an algorithm for deterministic continuous Markov Decision Processes with sparse rewards that computes the optimal policy exactly with no dependency on the size of the state space. The algorithm has time complexity of $O( |R|^3…

Machine Learning · Computer Science 2018-05-21 Joshua R. Bertram , Peng Wei

Safety in goal directed Reinforcement Learning (RL) settings has typically been handled through constraints over trajectories and have demonstrated good performance in primarily short horizon tasks. In this paper, we are specifically…

Artificial Intelligence · Computer Science 2024-01-10 Yuxiao Lu , Arunesh Sinha , Pradeep Varakantham

Reinforcement Learning (RL) agents often struggle with inefficient exploration, particularly in environments with sparse rewards. Traditional exploration strategies can lead to slow learning and suboptimal performance because agents fail to…

Machine Learning · Computer Science 2026-03-31 Gaurav Chaudhary , Laxmidhar Behera , Washim Uddin Mondal

Despite its popularity in the reinforcement learning community, a provably convergent policy gradient method for continuous space-time control problems with nonlinear state dynamics has been elusive. This paper proposes proximal gradient…

Optimization and Control · Mathematics 2022-12-27 Christoph Reisinger , Wolfgang Stockinger , Yufei Zhang

In constrained reinforcement learning (C-RL), an agent seeks to learn from the environment a policy that maximizes the expected cumulative reward while satisfying minimum requirements in secondary cumulative reward constraints. Several…

Machine Learning · Computer Science 2022-12-06 Tianqi Zheng , Pengcheng You , Enrique Mallada

Several challenges make it difficult for sparse neural networks to compete with dense models. First, setting a large fraction of weights to zero impairs forward and gradient signal propagation. Second, sparse studies often need to test…

Machine Learning · Computer Science 2026-02-04 Nolan Dey , Shane Bergsma , Joel Hestness

Reinforcement learning (RL) with sparse and deceptive rewards is challenging because non-zero rewards are rarely obtained. Hence, the gradient calculated by the agent can be stochastic and without valid information. Recent studies that…

Machine Learning · Computer Science 2024-02-08 Guojian Wang , Faguo Wu , Xiao Zhang , Jianxiang Liu

Reward sparsity in long-horizon reinforcement learning (RL) tasks remains a significant challenge, while existing outcome-based reward shaping struggles to define meaningful immediate rewards without introducing bias or requiring explicit…

Machine Learning · Computer Science 2025-08-15 Zetian Sun , Dongfang Li , Zhuoen Chen , Yuhuai Qin , Baotian Hu

Direct alignment algorithms have proven an effective step for aligning language models to human-desired behaviors. Current variants of the Direct Preference Optimization objective have focused on a strict setting where all tokens are…

Computation and Language · Computer Science 2025-11-03 Fenia Christopoulou , Ronald Cardenas , Gerasimos Lampouras , Haitham Bou-Ammar , Jun Wang

Stochastic first-order methods are standard for training large-scale machine learning models. Random behavior may cause a particular run of an algorithm to result in a highly suboptimal objective value, whereas theoretical guarantees are…

Optimization and Control · Mathematics 2024-09-02 Eduard Gorbunov , Marina Danilova , Innokentiy Shibaev , Pavel Dvurechensky , Alexander Gasnikov

Efficient and effective learning is one of the ultimate goals of the deep reinforcement learning (DRL), although the compromise has been made in most of the time, especially for the application of robot manipulations. Learning is always…

Machine Learning · Computer Science 2020-03-06 Yongle Luo , Kun Dong , Lili Zhao , Zhiyong Sun , Chao Zhou , Bo Song

Identifying homogeneous subgroups of variables can be challenging in high dimensional data analysis with highly correlated predictors. We propose a new method called Hexagonal Operator for Regression with Shrinkage and Equality Selection,…

Machine Learning · Statistics 2013-02-04 Woncheol Jang , Johan Lim , Nicole A. Lazar , Ji Meng Loh , Donghyeon Yu

We propose a novel hybrid stochastic policy gradient estimator by combining an unbiased policy gradient estimator, the REINFORCE estimator, with another biased one, an adapted SARAH estimator for policy optimization. The hybrid policy…

Machine Learning · Computer Science 2020-09-23 Nhan H. Pham , Lam M. Nguyen , Dzung T. Phan , Phuong Ha Nguyen , Marten van Dijk , Quoc Tran-Dinh

Long-horizon precision manipulation in laboratory automation, such as pipette tip attachment and liquid transfer, requires policies that respect strict procedural logic while operating in continuous, high-dimensional state spaces. However,…

Robotics · Computer Science 2026-03-03 Yibo Qiu , Shu'ang Sun , Haoliang Ye , Ronald X Xu , Mingzhai Sun

We study the distributed stochastic optimization (DSO) problem under a heavy-tailed noise condition by utilizing a multi-agent system. Despite the extensive research on DSO algorithms used to solve DSO problems under light-tailed noise…

Optimization and Control · Mathematics 2025-09-23 Zhan Yu , Lan Liao , Deming Yuan , Daniel W. C. Ho , Ding-Xuan Zhou

Recent advances in constrained reinforcement learning (RL) have endowed reinforcement learning with certain safety guarantees. However, deploying existing constrained RL algorithms in continuous control tasks with general hard constraints…

Machine Learning · Computer Science 2023-12-22 Shutong Ding , Jingya Wang , Yali Du , Ye Shi

Reinforcement learning (RL)-based quadrotor control policies have achieved impressive performance in tasks such as fast navigation in cluttered environments and drone racing, where the focus is on speed and agility. However, in several…

We address the application of stochastic optimization methods for the simultaneous control of parameter-dependent systems. In particular, we focus on the classical Stochastic Gradient Descent (SGD) approach of Robbins and Monro, and on the…

Optimization and Control · Mathematics 2023-02-08 Umberto Biccari , Ana Navarro-Quiles , Enrique Zuazua

It has been a recent trend to leverage the power of supervised learning (SL) towards more effective reinforcement learning (RL) methods. We propose a novel phasic approach by alternating online RL and offline SL for tackling sparse-reward…

Machine Learning · Computer Science 2022-06-27 Yunfei Li , Tian Gao , Jiaqi Yang , Huazhe Xu , Yi Wu

Data characterized by high dimensionality and sparsity are commonly used to describe real-world node interactions. Low-rank representation (LR) can map high-dimensional sparse (HDS) data to low-dimensional feature spaces and infer node…

Machine Learning · Computer Science 2024-08-30 Qicong Hu , Hao Wu