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Fivos Kalogiannis

7 accepted papers

2025

Policy Gradient Methods Converge Globally in Imperfect-Information Extensive-Form Games

NeurIPS 2025poster

Multi-agent reinforcement learning (MARL) has long been seen as inseparable from Markov games (Littman 1994). Yet, the most remarkable achievements of practical MARL have arguably been in extensive-form games (EFGs)---spanning games like Poker, Stratego, and Hanabi. At the same time, little is known…

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

Computing Nash Equilibria in Potential Games with Private Uncoupled Constraints

AAAI 2024technical

We consider the problem of computing Nash equilibria in potential games where each player's strategy set is subject to private uncoupled constraints. This scenario is frequently encountered in real-world applications like road network congestion games where individual drivers adhere to personal budg…

2024

Learning Equilibria in Adversarial Team Markov Games: A Nonconvex-Hidden-Concave Min-Max Optimization Problem

NeurIPS 2024poster

We study the problem of learning a Nash equilibrium (NE) in Markov games which is a cornerstone in multi-agent reinforcement learning (MARL). In particular, we focus on infinite-horizon adversarial team Markov games (ATMGs) in which agents that share a common reward function compete against a single…

Cited by 3SourcePDFScholar
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

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
2023

Zero-sum Polymatrix Markov Games: Equilibrium Collapse and Efficient Computation of Nash Equilibria

NeurIPS 2023poster

The works of (Daskalakis et al., 2009, 2022; Jin et al., 2022; Deng et al., 2023) indicate that computing Nash equilibria in multi-player Markov games is a computationally hard task. This fact raises the question of whether or not computational intractability can be circumvented if one focuses on s…

Cited by 12SourcePDFScholar