Dynamic Correlation Clustering in Sublinear Update Time
Vincent Cohen-Addad, Silvio Lattanzi, Andreas Maggiori, Nikos Parotsidis
TL;DR
The paper tackles dynamic correlation clustering in node streams, where nodes can be adversarially added and randomly deleted. It introduces a sublinear-time, constant-factor approximation built on an agreement-based framework with sampling and a Notify-based dynamic apparatus, achieving $O(\mathrm{polylog}\, n)$ amortized updates. The authors prove correctness and runtime guarantees and validate the approach with experiments on real-world graphs, showing robust performance across varying densities. This work lays a foundation for scalable clustering in evolving networks and opens questions on extending sublinear guarantees to more adversarial settings and further amortization improvements.
Abstract
We study the classic problem of correlation clustering in dynamic node streams. In this setting, nodes are either added or randomly deleted over time, and each node pair is connected by a positive or negative edge. The objective is to continuously find a partition which minimizes the sum of positive edges crossing clusters and negative edges within clusters. We present an algorithm that maintains an $O(1)$-approximation with $O$(polylog $n$) amortized update time. Prior to our work, Behnezhad, Charikar, Ma, and L. Tan achieved a $5$-approximation with $O(1)$ expected update time in edge streams which translates in node streams to an $O(D)$-update time where $D$ is the maximum possible degree. Finally we complement our theoretical analysis with experiments on real world data.
