Anas Barakat

Anas Barakat

Research Fellow

Singapore University of Technology and Design

Optimization · RL · Multi-Agent Learning

My research develops foundations and algorithms for sequential and strategic decision-making when objectives extend beyond expected cumulative reward, feedback is limited, and multiple adaptive agents interact. My work lies at the intersection of optimization, reinforcement learning, and learning in games, with a particular interest in emerging problems in modern AI, including post-training, AI alignment, and multi-agent learning.

I am currently a Research Fellow at Singapore University of Technology and Design, working with Georgios Piliouras and Antonios Varvitsiotis. Previously, I was a postdoctoral fellow at ETH Zurich working with Niao He. I received my PhD in mathematics and computer science from Institut Polytechnique de Paris (Télécom Paris), advised by Pascal Bianchi and Walid Hachem.

Research

Optimization for Sequential and Strategic Decision-Making

My research develops foundations and algorithms for decision-making beyond classical assumptions on objectives, feedback, and agent interactions, spanning three complementary directions:

  • Policy optimization beyond expected additive rewards: I study reinforcement learning and policy optimization when objectives depend nonlinearly on distributions of states, trajectories, or model responses, including general-utility RL and modern post-training.

  • Learning in strategic and dynamic environments: I study decentralized learning in nonstationary environments where multiple agents interact using game theory, including static, Markov and continuous-state dynamical games, with a focus on learning dynamics, stability, and convergence to equilibria.

  • Online learning with hidden structure and limited feedback: I study when learning remains possible despite apparent nonconvexity or restricted feedback. My work exploits latent structure such as hidden convexity and develops algorithms that learn directly from bandit or pairwise preference feedback.

Selected & Recent Research

Learning in Continuous Games from Pairwise Preference Feedback
Anas Barakat
Preprint · arXiv
Why Pass@k Optimization Can Degrade Pass@1: Prompt Interference in LLM Post-training
Anas Barakat, Souradip Chakraborty, Khushbu Pahwa, Amrit Singh Bedi
NeurIPS 2026 · arXiv
Online Learning on Hidden-Convex Losses via Algorithmic Equivalence: Optimal Regret, Geometric Barrier, and Bandit Feedback
Anas Barakat, Andreas Kontogiannis, Vasilis Pollatos, Ioannis Panageas, Antonios Varvitsiotis
NeurIPS 2026 · arXiv
Online Learning in Stabilized Linear Dynamical Games with Adversarial Disturbances
Anas Barakat, John Lazarsfeld, Georgios Piliouras, Antonios Varvitsiotis
NeurIPS 2026 · arXiv
Convex Markov Games and Beyond: New Proof of Existence, Characterization and Learning Algorithms for Nash Equilibria
Anas Barakat, Ioannis Panageas, Antonios Varvitsiotis
AISTATS 2026 · Proceedings
On the Global Optimality of Policy Gradient Methods in General Utility Reinforcement Learning
Anas Barakat, Souradip Chakraborty, Peihong Yu, Pratap Tokekar, Amrit Singh Bedi
NeurIPS 2025 · Proceedings
Reinforcement Learning with General Utilities: Simpler Variance Reduction and Large State-Action Space
Anas Barakat, Ilyas Fatkhullin, Niao He
ICML 2023 · Proceedings

For a complete list of my publications, see below or my Google Scholar.

News

10/2026
Selected as a Top Reviewer at NeurIPS 2026.
10/2026
New preprint: Learning in Continuous Games from Pairwise Preference Feedback. arXiv
09/2026
Four papers accepted at NeurIPS 2026 on LLM post-training, online learning, and learning in games.
09/2026
Invited to serve as an Area Chair for ICLR 2027.
07/2026
Policy Gradients for Cumulative Prospect Theory in Reinforcement Learning accepted to TMLR.
05/2026
New preprint: Online Learning on Hidden-Convex Losses via Algorithmic Equivalence: Optimal Regret, Geometric Barrier, and Bandit Feedback. arXiv
05/2026
Recognized as a Gold Reviewer at ICML 2026.
02/2026
New preprint: Why Pass@k Optimization Can Degrade Pass@1: Prompt Interference in LLM Post-training. arXiv
02/2026
Optimistic Online Learning in Symmetric Cone Games accepted to TMLR. Paper
01/2026
Convex Markov Games and Beyond accepted to AISTATS 2026. arXiv
10/2025
Designed and taught a new course with John Lazarsfeld and Iosif Sakos: Online Learning and Learning in Games.
09/2025
On the Global Optimality of Policy Gradient Methods in General Utility Reinforcement Learning accepted to NeurIPS 2025.

Experience and Background

2024–present
Research Fellow
Singapore University of Technology and Design
Working with Antonios Varvitsiotis.
2022–2024
Postdoctoral Fellow
ETH Zürich, Department of Computer Science
Worked with Niao He.
2018–2021
Ph.D. in Applied Mathematics and Computer Science
Institut Polytechnique de Paris (Télécom Paris)
Advised by Pascal Bianchi and Walid Hachem.

Here is my CV for more information.

Research

Publications

Policy Optimization Beyond Expected Additive Rewards

I study policy optimization when objectives depend nonlinearly on the distribution of trajectories or model responses, rather than on expected cumulative reward alone. My work develops scalable and globally convergent methods for general utility reinforcement learning, risk-sensitive objectives, and modern post-training objectives.

Why Pass@k Optimization Can Degrade Pass@1: Prompt Interference in LLM Post-training
Anas Barakat , Souradip Chakraborty , Khushbu Pahwa , Amrit Singh Bedi
NeurIPS 2026 · arXiv
Policy Gradients for Cumulative Prospect Theory in Reinforcement Learning
Olivier Lepel , Anas Barakat
Transactions on Machine Learning Research 2026 · Journal · arXiv · Slides
On the Global Optimality of Policy Gradient Methods in General Utility Reinforcement Learning
Anas Barakat , Souradip Chakraborty , Peihong Yu , Pratap Tokekar , Amrit Singh Bedi
NeurIPS 2025 · Proceedings · arXiv · Poster
Policy Mirror Descent with Lookahead
Kimon Protopapas , Anas Barakat
NeurIPS 2024 · Proceedings · arXiv · Poster
Reinforcement Learning with General Utilities: Simpler Variance Reduction and Large State-Action Space
Anas Barakat , Ilyas Fatkhullin , Niao He
ICML 2023 · Proceedings · arXiv · Slides · Poster
Stochastic Policy Gradient Methods: Improved Sample Complexity for Fisher-non-degenerate Policies
Ilyas Fatkhullin , Anas Barakat , Anastasia Kireeva , Niao He
ICML 2023 · Proceedings · arXiv · Poster
Analysis of a Target-Based Actor-Critic Algorithm with Linear Function Approximation
Anas Barakat , Pascal Bianchi , Julien Lehmann
AISTATS 2022 · Proceedings · arXiv · Poster

Learning in Strategic and Dynamic Environments

I study decentralized learning in strategic environments, from static games to Markov and continuous-state dynamical games. My work uses geometric and game-theoretic structure to understand when learning dynamics converge, cycle, or become unstable, and to design algorithms with equilibrium and regret guarantees.

When and Why is Optimistic Multiplicative Weights Slow? The Geometry of Energy Dissipation
John Lazarsfeld , Anas Barakat , Georgios Piliouras , Antonios Varvitsiotis , Andre Wibisono
NeurIPS 2026 · arXiv
Convex Markov Games and Beyond: New Proof of Existence, Characterization and Learning Algorithms for Nash Equilibria
Anas Barakat , Ioannis Panageas , Antonios Varvitsiotis
AISTATS 2026 · arXiv
Online Learning in Stabilized Linear Dynamical Games with Adversarial Disturbances
Anas Barakat , John Lazarsfeld , Georgios Piliouras , Antonios Varvitsiotis
NeurIPS 2026 · arXiv · Slides
Optimistic Online Learning in Symmetric Cone Games
Anas Barakat , Wayne Lin , John Lazarsfeld , Antonios Varvitsiotis
Transactions on Machine Learning Research 2026 · Journal · arXiv · Slides
Learning Zero-Sum Linear Quadratic Games with Improved Sample Complexity and Last Iterate Convergence
Jiduan Wu , Anas Barakat , Ilyas Fatkhullin , Niao He
SIAM Journal on Control and Optimization 63 (5), 3244-3271 · Journal · arXiv
Independent Policy Mirror Descent for Markov Potential Games: Scaling to Large Number of Players
Pragnya Alatur , Anas Barakat* , Niao He
IEEE CDC 2024. *corresponding author · Proceedings · arXiv · Slides
Independent Learning in Constrained Markov Potential Games
Philip Jordan , Anas Barakat , Niao He
AISTATS 2024 · Proceedings · arXiv · Slides · Poster
Learning Zero-Sum Linear Quadratic Games with Improved Sample Complexity
Jiduan Wu , Anas Barakat , Ilyas Fatkhullin , Niao He
IEEE CDC 2023 · Proceedings · arXiv

Online Learning with Hidden Structure and Limited Feedback

I study online learning when favorable structure may be hidden and feedback is limited or indirect. My work asks when latent geometry can restore tractability, when weak feedback—such as pairwise preferences—fundamentally limits what can be identified or learned, and how to design learning objectives and algorithms that remain meaningful under such informational constraints.

Learning in Continuous Games from Pairwise Preference Feedback
Anas Barakat
Preprint · arXiv
Online Learning on Hidden-Convex Losses via Algorithmic Equivalence: Optimal Regret, Geometric Barrier, and Bandit Feedback
Anas Barakat , Andreas Kontogiannis , Vasilis Pollatos , Ioannis Panageas , Antonios Varvitsiotis
NeurIPS 2026 · arXiv

Earlier Work: Stochastic Optimization

My earlier work studied stochastic approximation and non-convex optimization, including adaptive methods and dynamical systems perspectives on stochastic algorithms.

Stochastic optimization with momentum: convergence, fluctuations, and traps avoidance
Anas Barakat , Pascal Bianchi , Walid Hachem , Sholom Schechtman
Electronic Journal of Statistics 15 (2), 3892-3947 · arXiv · Journal
Convergence and Dynamical Behavior of the ADAM Algorithm for Non-Convex Stochastic Optimization
Anas Barakat , Pascal Bianchi
SIAM Journal on Optimization, 31 (1), 244-274 · arXiv · Journal · Slides · Poster
Convergence Rates of a Momentum Algorithm with Bounded Adaptive Step Size for Non-Convex Optimization
Anas Barakat , Pascal Bianchi
ACML 2020 · Proceedings · arXiv · Slides · Poster

Talks

Invited talk - 5th Symposium on Machine Learning and Dynamical Systems
Invited talk - ICCOPT 2025
Invited talk - Learning Theory and Applications Workshop, NTU
Invited talk - Finance and RL Talks
Invited talk - 4th Symposium on Machine Learning and Dynamical Systems

Student Mentoring

  • Olivier Lepel — Master’s thesis, Mar.–Sep. 2024
    Policy Gradients for Cumulative Prospect Theory in Reinforcement Learning. TMLR 2026.
    Currently: Data Scientist at BCG.

  • Kimon Protopapas — Master’s semester project, Sep. 2023–Jan. 2024
    Policy Mirror Descent with Lookahead. NeurIPS 2024.
    Currently: Research Intern at University of Basel.

  • Philip Jordan — Master’s thesis, May–Dec. 2023
    Independent Learning in Constrained Markov Potential Games. AISTATS 2024.
    Currently: PhD student at EPFL.

  • Jiduan Wu — Master’s thesis, Oct. 2022–Mar. 2023
    Learning Zero-Sum Linear Quadratic Games with Improved Sample Complexity and Last-Iterate Convergence. IEEE Conference on Decision and Control (CDC) 2023, SIAM Journal on Control and Optimization, 2025.
    Currently: PhD student at Max Planck ETH Center for Learning Systems.

  • Harish Rajagopal — Master’s thesis, Mar.–Sep. 2022
    Multistage Step Size Scheduling for Minimax Problems.
    Currently: Quantitative Technologist at Qube Research & Technologies.

  • Julien Lehmann — Master’s thesis, May–Oct. 2021
    Analysis of a Target-Based Actor-Critic Algorithm with Linear Function Approximation. AISTATS 2022.
    Currently: Research Engineer at OCamlPro.

Teaching

SUTD (2024-2025):

ETH Zurich (2022-2024):

Télécom Paris (2018-2021): Teaching Assistant

Optimization for Machine Learning (graduate level), Statistics (graduate level), Probabilities (undergraduate level).

Academic Service

  • Area Chair: ICLR 2027.
  • Conference Reviewing: NeurIPS (‘22, ‘23, ‘25, Top Reviewer ‘26), ICML (‘25, Gold Reviewer ‘26), ICLR (‘25, ‘26), AISTATS (Top Reviewer ‘22, ‘24, ‘25, ‘26), EC (‘26).
  • Journal Reviewing: Journal of Machine Learning Research (JMLR), Transactions on Machine Learning Research (TMLR), Mathematical Programming, SIAM Journal on Optimization (SIOPT), Journal of Optimization Theory and Applications (JOTA), IEEE Transactions on Automatic Control.