Search Results for author: Tamer Başar

Found 47 papers, 5 papers with code

Control Theoretic Approach to Fine-Tuning and Transfer Learning

no code implementations17 Apr 2024 Erkan Bayram, Shenyu Liu, Mohamed-Ali Belabbas, Tamer Başar

Given a training set in the form of a paired $(\mathcal{X},\mathcal{Y})$, we say that the control system $\dot{x} = f(x, u)$ has learned the paired set via the control $u^*$ if the system steers each point of $\mathcal{X}$ to its corresponding target in $\mathcal{Y}$.

Transfer Learning

Decision Transformer as a Foundation Model for Partially Observable Continuous Control

no code implementations3 Apr 2024 Xiangyuan Zhang, Weichao Mao, Haoran Qiu, Tamer Başar

Closed-loop control of nonlinear dynamical systems with partial-state observability demands expert knowledge of a diverse, less standardized set of theoretical tools.

Continuous Control Zero-shot Generalization

Policy Optimization finds Nash Equilibrium in Regularized General-Sum LQ Games

no code implementations25 Mar 2024 Muhammad Aneeq uz Zaman, Shubham Aggarwal, Melih Bastopcu, Tamer Başar

In this paper, we investigate the impact of introducing relative entropy regularization on the Nash Equilibria (NE) of General-Sum $N$-agent games, revealing the fact that the NE of such games conform to linear Gaussian policies.

Reinforcement Learning (RL)

Independent RL for Cooperative-Competitive Agents: A Mean-Field Perspective

no code implementations17 Mar 2024 Muhammad Aneeq uz Zaman, Alec Koppel, Mathieu Laurière, Tamer Başar

This MFTG NE is then shown to be $\mathcal{O}(1/M)$-NE for the finite population game where $M$ is a lower bound on the number of agents in each team.

Problem Decomposition Reinforcement Learning (RL)

Learning How to Strategically Disclose Information

no code implementations13 Mar 2024 Raj Kiriti Velicheti, Melih Bastopcu, S. Rasoul Etesami, Tamer Başar

In this work, we consider an online version of information design where a sender interacts with a receiver of an unknown type who is adversarially chosen at each round.

Policy Optimization for PDE Control with a Warm Start

no code implementations1 Mar 2024 Xiangyuan Zhang, Saviz Mowlavi, Mouhacine Benosman, Tamer Başar

The PO step fine-tunes the model-based controller to compensate for the modeling error from dimensionality reduction.

Dimensionality Reduction

Controlgym: Large-Scale Control Environments for Benchmarking Reinforcement Learning Algorithms

1 code implementation30 Nov 2023 Xiangyuan Zhang, Weichao Mao, Saviz Mowlavi, Mouhacine Benosman, Tamer Başar

This project serves the learning for dynamics & control (L4DC) community, aiming to explore key questions: the convergence of RL algorithms in learning control policies; the stability and robustness issues of learning-based controllers; and the scalability of RL algorithms to high- and potentially infinite-dimensional systems.

Benchmarking OpenAI Gym +2

Global Convergence of Receding-Horizon Policy Search in Learning Estimator Designs

1 code implementation9 Sep 2023 Xiangyuan Zhang, Saviz Mowlavi, Mouhacine Benosman, Tamer Başar

We introduce the receding-horizon policy gradient (RHPG) algorithm, the first PG algorithm with provable global convergence in learning the optimal linear estimator designs, i. e., the Kalman filter (KF).

Large Population Games on Constrained Unreliable Networks

no code implementations16 Mar 2023 Shubham Aggarwal, Muhammad Aneeq uz Zaman, Melih Bastopcu, Tamer Başar

A Base station (BS) actively schedules agent communications over the network by minimizing a weighted Age of Information (WAoI) based cost function under a capacity limit $\mathcal{C} < N$ on the number of transmission attempts at each instant.

Scheduling

Revisiting LQR Control from the Perspective of Receding-Horizon Policy Gradient

no code implementations25 Feb 2023 Xiangyuan Zhang, Tamer Başar

We revisit in this paper the discrete-time linear quadratic regulator (LQR) problem from the perspective of receding-horizon policy gradient (RHPG), a newly developed model-free learning framework for control applications.

Learning the Kalman Filter with Fine-Grained Sample Complexity

no code implementations30 Jan 2023 Xiangyuan Zhang, Bin Hu, Tamer Başar

We develop the first end-to-end sample complexity of model-free policy gradient (PG) methods in discrete-time infinite-horizon Kalman filtering.

Robust Reinforcement Learning for Risk-Sensitive Linear Quadratic Gaussian Control

no code implementations5 Dec 2022 Leilei Cui, Tamer Başar, Zhong-Ping Jiang

This paper proposes a novel robust reinforcement learning framework for discrete-time linear systems with model mismatch that may arise from the sim-to-real gap.

reinforcement-learning Reinforcement Learning (RL)

An Improved Analysis of (Variance-Reduced) Policy Gradient and Natural Policy Gradient Methods

no code implementations NeurIPS 2020 Yanli Liu, Kaiqing Zhang, Tamer Başar, Wotao Yin

In this paper, we revisit and improve the convergence of policy gradient (PG), natural PG (NPG) methods, and their variance-reduced variants, under general smooth policy parametrizations.

Policy Gradient Methods

Weighted Age of Information based Scheduling for Large Population Games on Networks

no code implementations26 Sep 2022 Shubham Aggarwal, Muhammad Aneeq uz Zaman, Melih Bastopcu, Tamer Başar

Due to a hard bandwidth constraint on the number of transmissions through the network, at most $R_d < N$ agents can concurrently access their state information through the network.

Scheduling

Oracle-free Reinforcement Learning in Mean-Field Games along a Single Sample Path

no code implementations24 Aug 2022 Muhammad Aneeq uz Zaman, Alec Koppel, Sujay Bhatt, Tamer Başar

Given that the underlying Markov Decision Process (MDP) of the agent is communicating, we provide finite sample convergence guarantees in terms of convergence of the mean-field and control policy to the mean-field equilibrium.

reinforcement-learning Reinforcement Learning (RL)

Modeling and Analysis of a Coupled SIS Bi-Virus Model

no code implementations23 Jul 2022 Sebin Gracy, Philip E. Paré, Ji Liu, Henrik Sandberg, Carolyn L. Beck, Karl Henrik Johansson, Tamer Başar

We establish a sufficient condition and multiple necessary conditions for local exponential convergence to the boundary equilibrium (i. e., one virus persists, the other one dies out) of each virus.

Convergence and sample complexity of natural policy gradient primal-dual methods for constrained MDPs

no code implementations6 Jun 2022 Dongsheng Ding, Kaiqing Zhang, Jiali Duan, Tamer Başar, Mihailo R. Jovanović

We study sequential decision making problems aimed at maximizing the expected total reward while satisfying a constraint on the expected total utility.

Decision Making

Linear Quadratic Mean-Field Games with Communication Constraints

no code implementations11 Mar 2022 Shubham Aggarwal, Muhammad Aneeq uz Zaman, Tamer Başar

Since the complexity of solving the game increases with the number of agents, we use the Mean-Field Game paradigm to solve it.

Scheduling

Finite-Sample Analysis of Decentralized Q-Learning for Stochastic Games

no code implementations15 Dec 2021 Zuguang Gao, Qianqian Ma, Tamer Başar, John R. Birge

With linear function approximation, the results are for convergence to a linear approximated equilibrium - a new notion of equilibrium that we propose - which describes that each agent's policy is a best reply (to other agents) within a linear space.

Multi-agent Reinforcement Learning Q-Learning

Provably Efficient Reinforcement Learning in Decentralized General-Sum Markov Games

no code implementations12 Oct 2021 Weichao Mao, Tamer Başar

We show that the agents can find an $\epsilon$-approximate CCE in at most $\widetilde{O}( H^6S A /\epsilon^2)$ episodes, where $S$ is the number of states, $A$ is the size of the largest individual action space, and $H$ is the length of an episode.

Multi-agent Reinforcement Learning Q-Learning +2

On Improving Model-Free Algorithms for Decentralized Multi-Agent Reinforcement Learning

no code implementations12 Oct 2021 Weichao Mao, Lin F. Yang, Kaiqing Zhang, Tamer Başar

Multi-agent reinforcement learning (MARL) algorithms often suffer from an exponential sample complexity dependence on the number of agents, a phenomenon known as \emph{the curse of multiagents}.

Multi-agent Reinforcement Learning Q-Learning +3

Adversarial Linear-Quadratic Mean-Field Games over Multigraphs

no code implementations29 Sep 2021 Muhammad Aneeq uz Zaman, Sujay Bhatt, Tamer Başar

In this paper, we propose a game between an exogenous adversary and a network of agents connected via a multigraph.

Partial Observability Approach for the Optimal Transparency Problem in Multi-agent Systems

no code implementations18 Jan 2021 Sadegh Arefizadeh, Sadjaad Ozgoli, Sadegh Bolouki, Tamer Başar

A principal is tasked to optimize the network's performance by controlling the information available to each agent with regard to other agents' latest actions.

Dynamical Systems Systems and Control Systems and Control Optimization and Control

Derivative-Free Policy Optimization for Linear Risk-Sensitive and Robust Control Design: Implicit Regularization and Sample Complexity

no code implementations NeurIPS 2021 Kaiqing Zhang, Xiangyuan Zhang, Bin Hu, Tamer Başar

Direct policy search serves as one of the workhorses in modern reinforcement learning (RL), and its applications in continuous control tasks have recently attracted increasing attention.

Continuous Control Multi-agent Reinforcement Learning +2

Model-Based Multi-Agent RL in Zero-Sum Markov Games with Near-Optimal Sample Complexity

no code implementations NeurIPS 2020 Kaiqing Zhang, Sham M. Kakade, Tamer Başar, Lin F. Yang

This is in contrast to the usual reward-aware setting, with a $\tilde\Omega(|S|(|A|+|B|)(1-\gamma)^{-3}\epsilon^{-2})$ lower bound, where this model-based approach is near-optimal with only a gap on the $|A|,|B|$ dependence.

Model-based Reinforcement Learning Reinforcement Learning (RL)

POLY-HOOT: Monte-Carlo Planning in Continuous Space MDPs with Non-Asymptotic Analysis

no code implementations NeurIPS 2020 Weichao Mao, Kaiqing Zhang, Qiaomin Xie, Tamer Başar

Monte-Carlo planning, as exemplified by Monte-Carlo Tree Search (MCTS), has demonstrated remarkable performance in applications with finite spaces.

Information State Embedding in Partially Observable Cooperative Multi-Agent Reinforcement Learning

1 code implementation2 Apr 2020 Weichao Mao, Kaiqing Zhang, Erik Miehling, Tamer Başar

To enable the development of tractable algorithms, we introduce the concept of an information state embedding that serves to compress agents' histories.

Multi-agent Reinforcement Learning reinforcement-learning +1

Fully Asynchronous Policy Evaluation in Distributed Reinforcement Learning over Networks

no code implementations1 Mar 2020 Xingyu Sha, Jia-Qi Zhang, Keyou You, Kaiqing Zhang, Tamer Başar

This paper proposes a \emph{fully asynchronous} scheme for the policy evaluation problem of distributed reinforcement learning (DisRL) over directed peer-to-peer networks.

reinforcement-learning Reinforcement Learning (RL)

Decentralized Multi-Agent Reinforcement Learning with Networked Agents: Recent Advances

no code implementations9 Dec 2019 Kaiqing Zhang, Zhuoran Yang, Tamer Başar

Multi-agent reinforcement learning (MARL) has long been a significant and everlasting research topic in both machine learning and control.

Decision Making Multi-agent Reinforcement Learning +2

Multi-Agent Reinforcement Learning: A Selective Overview of Theories and Algorithms

no code implementations24 Nov 2019 Kaiqing Zhang, Zhuoran Yang, Tamer Başar

Orthogonal to the existing reviews on MARL, we highlight several new angles and taxonomies of MARL theory, including learning in extensive-form games, decentralized MARL with networked agents, MARL in the mean-field regime, (non-)convergence of policy-based methods for learning in games, etc.

Autonomous Driving Decision Making +3

Non-Cooperative Inverse Reinforcement Learning

no code implementations NeurIPS 2019 Xiangyuan Zhang, Kaiqing Zhang, Erik Miehling, Tamer Başar

Through interacting with the more informed player, the less informed player attempts to both infer, and act according to, the true objective function.

reinforcement-learning Reinforcement Learning (RL)

Online Planning for Decentralized Stochastic Control with Partial History Sharing

no code implementations6 Aug 2019 Kaiqing Zhang, Erik Miehling, Tamer Başar

To demonstrate the applicability of the model, we propose a novel collaborative intrusion response model, where multiple agents (defenders) possessing asymmetric information aim to collaboratively defend a computer network.

Decision Making

A Communication-Efficient Multi-Agent Actor-Critic Algorithm for Distributed Reinforcement Learning

no code implementations6 Jul 2019 Yixuan Lin, Kaiqing Zhang, Zhuoran Yang, Zhaoran Wang, Tamer Başar, Romeil Sandhu, Ji Liu

This paper considers a distributed reinforcement learning problem in which a network of multiple agents aim to cooperatively maximize the globally averaged return through communication with only local neighbors.

reinforcement-learning Reinforcement Learning (RL)

Global Convergence of Policy Gradient Methods to (Almost) Locally Optimal Policies

no code implementations19 Jun 2019 Kaiqing Zhang, Alec Koppel, Hao Zhu, Tamer Başar

Under a further strict saddle points assumption, this result establishes convergence to essentially locally-optimal policies of the underlying problem, and thus bridges the gap in existing literature on the convergence of PG methods.

Autonomous Driving Policy Gradient Methods

Policy Optimization Provably Converges to Nash Equilibria in Zero-Sum Linear Quadratic Games

no code implementations NeurIPS 2019 Kaiqing Zhang, Zhuoran Yang, Tamer Başar

To the best of our knowledge, this work appears to be the first one to investigate the optimization landscape of LQ games, and provably show the convergence of policy optimization methods to the Nash equilibria.

Communication-Efficient Policy Gradient Methods for Distributed Reinforcement Learning

no code implementations7 Dec 2018 Tianyi Chen, Kaiqing Zhang, Georgios B. Giannakis, Tamer Başar

This paper deals with distributed policy optimization in reinforcement learning, which involves a central controller and a group of learners.

Distributed Computing Multi-agent Reinforcement Learning +3

Finite-Sample Analysis For Decentralized Batch Multi-Agent Reinforcement Learning With Networked Agents

no code implementations6 Dec 2018 Kaiqing Zhang, Zhuoran Yang, Han Liu, Tong Zhang, Tamer Başar

This work appears to be the first finite-sample analysis for batch MARL, a step towards rigorous theoretical understanding of general MARL algorithms in the finite-sample regime.

Multi-agent Reinforcement Learning reinforcement-learning +1

Distributed Learning of Average Belief Over Networks Using Sequential Observations

no code implementations19 Nov 2018 Kaiqing Zhang, Yang Liu, Ji Liu, Mingyan Liu, Tamer Başar

This paper addresses the problem of distributed learning of average belief with sequential observations, in which a network of $n>1$ agents aim to reach a consensus on the average value of their beliefs, by exchanging information only with their neighbors.

Fully Decentralized Multi-Agent Reinforcement Learning with Networked Agents

5 code implementations ICML 2018 Kaiqing Zhang, Zhuoran Yang, Han Liu, Tong Zhang, Tamer Başar

To this end, we propose two decentralized actor-critic algorithms with function approximation, which are applicable to large-scale MARL problems where both the number of states and the number of agents are massively large.

Multi-agent Reinforcement Learning reinforcement-learning +1

Reliable Intersection Control in Non-cooperative Environments

no code implementations22 Feb 2018 Muhammed O. Sayin, Chung-Wei Lin, Shinichi Shiraishi, Tamer Başar

We propose a reliable intersection control mechanism for strategic autonomous and connected vehicles (agents) in non-cooperative environments.

Team-Optimal Distributed MMSE Estimation in General and Tree Networks

no code implementations3 Oct 2016 Muhammed O. Sayin, Suleyman S. Kozat, Tamer Başar

Finally, in the numerical examples, we demonstrate the superior performance of the introduced algorithms in the finite-horizon MSE sense due to optimal estimation.

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