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Emmanouil-Vasileios Vlatakis-Gkaragkounis

16 accepted papers

2026

Shuffling the Data, Extrapolating the Step: Sharper Bias In Constant Step-Size SGD

ICLR 2026poster

From adversarial robustness to multi-agent learning, many machine learning tasks can be cast as finite-sum min–max optimization or, more generally, as variational inequality problems (VIPs). Owing to their simplicity and scalability, stochastic gradient methods with constant step size are widely us…

Cited by 0SourceScholar
2026

Sparks of Cooperative Reasoning: LLMs as Strategic Hanabi Agents

ICML 2026poster

Cooperative reasoning under incomplete information remains complex for both humans and multi-agent AI, requiring agents to transcend individual logic in favor of recursive Theory-of-Mind (ToM) and strategic coordination. To investigate these challenges, we conduct a large-scale evaluation of 17 stat…

Cited by 0SourceScholar
2025

Solving Neural Min-Max Games: The Role of Architecture, Initialization & Dynamics

NeurIPS 2025spotlight

Many emerging applications—such as adversarial training, AI alignment, and robust optimization—can be framed as zero-sum games between neural nets, with von Neumann–Nash equilibria (NE) capturing the desirable system behavior. While such games often involve non-convex non-concave objectives, empiri…

Cited by 0SourceScholar
2025

Solving Zero-Sum Convex Markov Games

ICML 2025poster

We contribute the first provable guarantees of global convergence to Nash equilibria (NE) in two-player zero-sum convex Markov games (cMGs) by using independent policy gradient methods. Convex Markov games, recently defined by Gemp et al.(2024), extend Markov decision processes to multi-agent settin…

Cited by 0SourcePDFScholar
2024

Contracting with a Learning Agent

NeurIPS 2024poster

Real-life contractual relations typically involve repeated interactions between the principal and agent, where, despite theoretical appeal, players rarely use complex dynamic strategies and instead manage uncertainty through learning algorithms. In this paper, we initiate the study of repeated cont…

Cited by 32SourcePDFScholar
2023

Efficiently Computing Nash Equilibria in Adversarial Team Markov Games

ICLR 2023top-5%

Computing Nash equilibrium policies is a central problem in multi-agent reinforcement learning that has received extensive attention both in theory and in practice. However, in light of computational intractability barriers in general-sum games, provable guarantees have been thus far either limited…

Cited by 23SourcePDFScholar
2023

Exploiting hidden structures in non-convex games for convergence to Nash equilibrium

NeurIPS 2023poster

A wide array of modern machine learning applications – from adversarial models to multi-agent reinforcement learning – can be formulated as non-cooperative games whose Nash equilibria represent the system’s desired operational states. Despite having a highly non-convex loss landscape, many cases of…

Cited by 5SourcePDFScholar
2023

Towards convergence to Nash equilibria in two-team zero-sum games

ICLR 2023poster

Contemporary applications of machine learning raise important and overlooked theoretical questions regarding optimization in two-team games. Formally, two-team zero-sum games are defined as multi-player games where players are split into two competing sets of agents, each experiencing a utility iden…

Cited by 7SourcePDFScholar
2022

First-Order Algorithms for Min-Max Optimization in Geodesic Metric Spaces

NeurIPS 2022accept

From optimal transport to robust dimensionality reduction, many machine learning applications can be cast into the min-max optimization problems over Riemannian manifolds. Though many min-max algorithms have been analyzed in the Euclidean setting, it has been elusive how these results translate to t…

Cited by 22SourcePDFScholar
2022

On the convergence of policy gradient methods to Nash equilibria in general stochastic games

NeurIPS 2022accept

Learning in stochastic games is a notoriously difficult problem because, in addition to each other's strategic decisions, the players must also contend with the fact that the game itself evolves over time, possibly in a very complicated manner. Because of this, the convergence properties of popular…

Cited by 22SourcePDFScholar
2021

On the Rate of Convergence of Regularized Learning in Games: From Bandits and Uncertainty to Optimism and Beyond

NeurIPS 2021poster

In this paper, we examine the convergence rate of a wide range of regularized methods for learning in games. To that end, we propose a unified algorithmic template that we call “follow the generalized leader” (FTGL), and which includes as special cases the canonical “follow the regularized leader” a…

Cited by 31SourcePDFScholar
2021

Solving Min-Max Optimization with Hidden Structure via Gradient Descent Ascent

NeurIPS 2021poster

Many recent AI architectures are inspired by zero-sum games, however, the behavior of their dynamics is still not well understood. Inspired by this, we study standard gradient descent ascent (GDA) dynamics in a specific class of non-convex non-concave zero-sum games, that we call hidden zero-sum gam…

Cited by 22SourcePDFScholar
2020

No-Regret Learning and Mixed Nash Equilibria: They Do Not Mix

NeurIPS 2020spotlight

Understanding the behavior of no-regret dynamics in general N-player games is a fundamental question in online learning and game theory. A folk result in the field states that, in finite games, the empirical frequency of play under no-regret learning converges to the game’s set of coarse correlated…

Cited by 57SourcePDFScholar
2020

Optimal Private Median Estimation under Minimal Distributional Assumptions

NeurIPS 2020spotlight

We study the fundamental task of estimating the median of an underlying distribution from a finite number of samples, under pure differential privacy constraints. We focus on distributions satisfying the minimal assumption that they have a positive density at a small neighborhood around the median.…

Cited by 24SourcePDFScholar
2019

Efficiently avoiding saddle points with zero order methods: No gradients required

NeurIPS 2019poster

We consider the case of derivative-free algorithms for non-convex optimization, also known as zero order algorithms, that use only function evaluations rather than gradients. For a wide variety of gradient approximators based on finite differences, we establish asymptotic convergence to second order…

2019

Poincaré Recurrence, Cycles and Spurious Equilibria in Gradient-Descent-Ascent for Non-Convex Non-Concave Zero-Sum Games

NeurIPS 2019spotlight

We study a wide class of non-convex non-concave min-max games that generalizes over standard bilinear zero-sum games. In this class, players control the inputs of a smooth function whose output is being applied to a bilinear zero-sum game. This class of games is motivated by the indirect nature of…