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Stratis Skoulakis

16 accepted papers

2025

Best of Both Worlds: Regret Minimization versus Minimax Play

ICML 2025poster

In this paper, we investigate the existence of online learning algorithms with bandit feedback that simultaneously guarantee $O(1)$ regret compared to a given comparator strategy, and $\tilde{O}(\sqrt{T})$ regret compared to any fixed strategy, where $T$ is the number of rounds. We provide the first…

Cited by 0SourcePDFScholar
2025

Continuous-Time Analysis of Heavy Ball Momentum in Min-Max Games

ICML 2025poster

Since Polyak's pioneering work, heavy ball (HB) momentum has been widely studied in minimization. However, its role in min-max games remains largely unexplored. As a key component of practical min-max algorithms like Adam, this gap limits their effectiveness. In this paper, we present a continuous-t…

Cited by 0SourcePDFScholar
2025

Optimism Without Regularization: Constant Regret in Zero-Sum Games

NeurIPS 2025poster

This paper studies the *optimistic* variant of Fictitious Play for learning in two-player zero-sum games. While it is known that Optimistic FTRL -- a *regularized* algorithm with a bounded stepsize parameter -- obtains constant regret in this setting, we show for the first time that similar, optima…

Cited by 0SourceScholar
2024

Efficient Continual Finite-Sum Minimization

ICLR 2024poster

Given a sequence of functions $f_1,\ldots,f_n$ with $f_i:\mathcal{D}\mapsto \mathbb{R}$, finite-sum minimization seeks a point ${x}^\star \in \mathcal{D}$ minimizing $\sum_{j=1}^nf_j(x)/n$. In this work, we propose a key twist into the finite-sum minimization, dubbed as *continual finite-sum minimiz…

Cited by 0SourcePDFScholar
2024

Imitation Learning in Discounted Linear MDPs without exploration assumptions

ICML 2024poster

We present a new algorithm for imitation learning in infinite horizon linear MDPs dubbed ILARL which greatly improves the bound on the number of trajectories that the learner needs to sample from the environment. In particular, we remove exploration assumptions required in previous works and we impr…

Cited by 4SourcePDFScholar
2024

Learning to Remove Cuts in Integer Linear Programming

ICML 2024poster

Cutting plane methods are a fundamental approach for solving integer linear programs (ILPs). In each iteration of such methods, additional linear constraints (cuts) are introduced to the constraint set with the aim of excluding the previous fractional optimal solution while not affecting the optimal…

2023

Alternation makes the adversary weaker in two-player games

NeurIPS 2023spotlight

Motivated by alternating game-play in two-player games, we study an altenating variant of the \textit{Online Linear Optimization} (OLO). In alternating OLO, a \textit{learner} at each round $t \in [n]$ selects a vector $x^t$ and then an \textit{adversary} selects a cost-vector $c^t \in [-1,1]^n$. T…

Cited by 3SourcePDFScholar
2023

Exponential Lower Bounds for Fictitious Play in Potential Games

NeurIPS 2023poster

Fictitious Play (FP) is a simple and natural dynamic for repeated play with many applications in game theory and multi-agent reinforcement learning. It was introduced by Brown and its convergence properties for two-player zero-sum games was established later by Robinson. Potential games [Monderer an…

Cited by 4SourcePDFScholar
2023

Maximum Independent Set: Self-Training through Dynamic Programming

NeurIPS 2023poster

This work presents a graph neural network (GNN) framework for solving the maximum independent set (MIS) problem, inspired by dynamic programming (DP). Specifically, given a graph, we propose a DP-like recursive algorithm based on GNNs that firstly constructs two smaller sub-graphs, predicts the one…

2023

Semi Bandit dynamics in Congestion Games: Convergence to Nash Equilibrium and No-Regret Guarantees.

ICML 2023oral

In this work, we propose introduce a variant of online stochastic gradient descent and prove it converges to Nash equilibria and simultaneously it has sublinear regret for the class of congestion games in the semi-bandit feedback setting. Our proposed method admits convergence rates depending only p…

2021

Estimating the Number of Induced Subgraphs from Incomplete Data and Neighborhood Queries

AAAI 2021technical

We consider a natural setting where network parameters are estimated from noisy and incomplete information about the network. More specifically, we investigate how we can efficiently estimate the number of small subgraphs (e.g., edges, triangles, etc.) based on full access to one or two noisy and in…

Cited by 0SourcePDFScholar
2021

Evolutionary Game Theory Squared: Evolving Agents in Endogenously Evolving Zero-Sum Games

AAAI 2021technical

The predominant paradigm in evolutionary game theory and more generally online learning in games is based on a clear distinction between a population of dynamic agents that interact given a fixed, static game. In this paper, we move away from the artificial divide between dynamic agents and static g…