Scalable Distributed Algorithms for Size-Constrained Submodular Maximization in the MapReduce and Adaptive Complexity Models

TL;DR

This paper develops scalable distributed algorithms for size-constrained submodular maximization, combining MapReduce and adaptive models, introducing new algorithms with linear query complexity and methods to handle larger constraints efficiently.

Contribution

It introduces the first distributed algorithm with linear query complexity and extends MapReduce algorithms to larger constraints with additional rounds.

Findings

Several sublinearly adaptive algorithms satisfy the MR consistency property.

A distributed algorithm with linear query complexity is proposed.

A method to increase the maximum cardinality constraint with more MR rounds.

Abstract

Distributed maximization of a submodular function in the MapReduce (MR) model has received much attention, culminating in two frameworks that allow a centralized algorithm to be run in the MR setting without loss of approximation, as long as the centralized algorithm satisfies a certain consistency property -- which had previously only been known to be satisfied by the standard greedy and continous greedy algorithms. A separate line of work has studied parallelizability of submodular maximization in the adaptive complexity model, where each thread may have access to the entire ground set. For the size-constrained maximization of a monotone and submodular function, we show that several sublinearly adaptive (highly parallelizable) algorithms satisfy the consistency property required to work in the MR setting, which yields practical, parallelizable and distributed algorithms. Separately, we develop the first distributed algorithm with linear query complexity for this problem. Finally, we provide a method to increase the maximum cardinality constraint for MR algorithms at the cost of additional MR rounds.