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Nicholas Bambos

15 accepted papers

2025

Multi-Agent Learning under Uncertainty: Recurrence vs. Concentration

NeurIPS 2025spotlight

In this paper, we examine the convergence landscape of multi-agent learning under uncertainty. Specifically, we analyze two stochastic models of regularized learning in continuous games—one in continuous and one in discrete time—with the aim of characterizing the long run behavior of the induced seq…

Cited by 0SourceScholar
2025

Robust Equilibria in Continuous Games: From Strategic to Dynamic Robustness

NeurIPS 2025poster

In this paper, we examine the robustness of Nash equilibria in continuous games, under both strategic and dynamic uncertainty. Starting with the former, we introduce the notion of a robust equilibrium as those equilibria that remain invariant to small—but otherwise arbitrary—perturbations to the gam…

Cited by 0SourceScholar
2024

Accelerated Regularized Learning in Finite N-Person Games

NeurIPS 2024poster

Motivated by the success of Nesterov's accelerated gradient algorithm for convex minimization problems, we examine whether it is possible to achieve similar performance gains in the context of online learning in games. To that end, we introduce a family of accelerated learning methods, which we call…

Cited by 0SourcePDFScholar
2023

Payoff-based Learning with Matrix Multiplicative Weights in Quantum Games

NeurIPS 2023poster

In this paper, we study the problem of learning in quantum games - and other classes of semidefinite games - with scalar, payoff-based feedback. For concreteness, we focus on the widely used matrix multiplicative weights (MMW) algorithm and, instead of requiring players to have full knowledge of the…

Cited by 1SourcePDFScholar
2023

Wasserstein Distributionally Robust Linear-Quadratic Estimation under Martingale Constraints

AISTATS 2023poster

We focus on robust estimation of the unobserved state of a discrete-time stochastic system with linear dynamics. A standard analysis of this estimation problem assumes a baseline innovation model; with Gaussian innovations we recover the Kalman filter. However, in many settings, there is insufficien…

Cited by 14SourcePDFScholar
2022

Queue Up Your Regrets: Achieving the Dynamic Capacity Region of Multiplayer Bandits

NeurIPS 2022accept

Abstract Consider $N$ cooperative agents such that for $T$ turns, each agent n takes an action $a_{n}$ and receives a stochastic reward $r_{n}\left(a_{1},\ldots,a_{N}\right)$. Agents cannot observe the actions of other agents and do not know even their own reward function. The agents can communicate…

Cited by 5SourcePDFScholar
2021

Online Learning for Load Balancing of Unknown Monotone Resource Allocation Games

ICML 2021spotlight

Consider N players that each uses a mixture of K resources. Each of the players’ reward functions includes a linear pricing term for each resource that is controlled by the game manager. We assume that the game is strongly monotone, so if each player runs gradient descent, the dynamics converge to a…

Cited by 9SourcePDFScholar
2020

My Fair Bandit: Distributed Learning of Max-Min Fairness with Multi-player Bandits

ICML 2020poster

Consider N cooperative but non-communicating players where each plays one out of M arms for T turns. Players have different utilities for each arm, representable as an NxM matrix. These utilities are unknown to the players. In each turn players receive noisy observations of their utility for their s…

Cited by 44SourcePDFScholar
2018

Distributed Asynchronous Optimization with Unbounded Delays: How Slow Can You Go?

ICML 2018oral

One of the most widely used optimization methods for large-scale machine learning problems is distributed asynchronous stochastic gradient descent (DASGD). However, a key issue that arises here is that of delayed gradients: when a “worker” node asynchronously contributes a gradient update to the “ma…

Cited by 72SourcePDFScholar
2018

Learning in Games with Lossy Feedback

NeurIPS 2018poster

We consider a game-theoretical multi-agent learning problem where the feedback information can be lost during the learning process and rewards are given by a broad class of games known as variationally stable games. We propose a simple variant of the classical online gradient descent algorithm, call…

Cited by 30SourcePDFScholar
2017

Countering Feedback Delays in Multi-Agent Learning

NeurIPS 2017poster

We consider a model of game-theoretic learning based on online mirror descent (OMD) with asynchronous and delayed feedback information. Instead of focusing on specific games, we consider a broad class of continuous games defined by the general equilibrium stability notion, which we call λ-variationa…

Cited by 36SourcePDFScholar
2017

Stochastic Mirror Descent in Variationally Coherent Optimization Problems

NeurIPS 2017poster

In this paper, we examine a class of non-convex stochastic optimization problems which we call variationally coherent, and which properly includes pseudo-/quasiconvex and star-convex optimization problems. To solve such problems, we focus on the widely used stochastic mirror descent (SMD) family of…

Cited by 108SourcePDFScholar