Water-Filling is Universally Minimax Optimal

Fuente: arXiv
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Main Authors: Banerjee, Siddhartha, Vuong, Ramiro N. Deo-Campo, Kleinberg, Robert
Format: Preprint
Published: 2026
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author Banerjee, Siddhartha
Vuong, Ramiro N. Deo-Campo
Kleinberg, Robert
author_facet Banerjee, Siddhartha
Vuong, Ramiro N. Deo-Campo
Kleinberg, Robert
contents Allocation of dynamically-arriving (i.e., online) divisible resources among a set of offline agents is a fundamental problem, with applications to online marketplaces, scheduling, portfolio selection, signal processing, and many other areas. The water-filling algorithm, which allocates an incoming resource to maximize the minimum load of compatible agents, is ubiquitous in many of these applications whenever the underlying objectives prefer more balanced solutions; however, the analysis and guarantees differ across settings. We provide a justification for the widespread use of water-filling by showing that it is a universally minimax optimal policy in a strong sense. Formally, our main result implies that water-filling is minimax optimal for a large class of objectives -- including both Schur-concave maximization and Schur-convex minimization -- under $α$-regret and competitive ratio measures. This optimality holds for every fixed tuple of agents and resource counts. Remarkably, water-filling achieves these guarantees as a myopic policy, remaining entirely agnostic to the objective function, agent count, and resource availability. Our techniques notably depart from the popular primal-dual analysis of online algorithms, and instead develop a novel way to apply the theory of majorization in online settings to achieve universality guarantees.
format Preprint
id arxiv_https___arxiv_org_abs_2603_26893
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Water-Filling is Universally Minimax Optimal
Banerjee, Siddhartha
Vuong, Ramiro N. Deo-Campo
Kleinberg, Robert
Data Structures and Algorithms
Computer Science and Game Theory
Machine Learning
Allocation of dynamically-arriving (i.e., online) divisible resources among a set of offline agents is a fundamental problem, with applications to online marketplaces, scheduling, portfolio selection, signal processing, and many other areas. The water-filling algorithm, which allocates an incoming resource to maximize the minimum load of compatible agents, is ubiquitous in many of these applications whenever the underlying objectives prefer more balanced solutions; however, the analysis and guarantees differ across settings. We provide a justification for the widespread use of water-filling by showing that it is a universally minimax optimal policy in a strong sense. Formally, our main result implies that water-filling is minimax optimal for a large class of objectives -- including both Schur-concave maximization and Schur-convex minimization -- under $α$-regret and competitive ratio measures. This optimality holds for every fixed tuple of agents and resource counts. Remarkably, water-filling achieves these guarantees as a myopic policy, remaining entirely agnostic to the objective function, agent count, and resource availability. Our techniques notably depart from the popular primal-dual analysis of online algorithms, and instead develop a novel way to apply the theory of majorization in online settings to achieve universality guarantees.
title Water-Filling is Universally Minimax Optimal
topic Data Structures and Algorithms
Computer Science and Game Theory
Machine Learning
url https://arxiv.org/abs/2603.26893