Approximate Tree Completion and Learning-Augmented Algorithms for Metric Minimum Spanning Trees

Fuente: arXiv
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Hauptverfasser: Veldt, Nate, Stanley, Thomas, Priest, Benjamin W., Steil, Trevor, Iwabuchi, Keita, Jayram, T. S., Sanders, Geoffrey
Format: Preprint
Veröffentlicht: 2025
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author Veldt, Nate
Stanley, Thomas
Priest, Benjamin W.
Steil, Trevor
Iwabuchi, Keita
Jayram, T. S.
Sanders, Geoffrey
author_facet Veldt, Nate
Stanley, Thomas
Priest, Benjamin W.
Steil, Trevor
Iwabuchi, Keita
Jayram, T. S.
Sanders, Geoffrey
contents Finding a minimum spanning tree (MST) for $n$ points in an arbitrary metric space is a fundamental primitive for hierarchical clustering and many other ML tasks, but this takes $Ω(n^2)$ time to even approximate. We introduce a framework for metric MSTs that first (1) finds a forest of disconnected components using practical heuristics, and then (2) finds a small weight set of edges to connect disjoint components of the forest into a spanning tree. We prove that optimally solving the second step still takes $Ω(n^2)$ time, but we provide a subquadratic 2.62-approximation algorithm. In the spirit of learning-augmented algorithms, we then show that if the forest found in step (1) overlaps with an optimal MST, we can approximate the original MST problem in subquadratic time, where the approximation factor depends on a measure of overlap. In practice, we find nearly optimal spanning trees for a wide range of metrics, while being orders of magnitude faster than exact algorithms.
format Preprint
id arxiv_https___arxiv_org_abs_2502_12993
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Approximate Tree Completion and Learning-Augmented Algorithms for Metric Minimum Spanning Trees
Veldt, Nate
Stanley, Thomas
Priest, Benjamin W.
Steil, Trevor
Iwabuchi, Keita
Jayram, T. S.
Sanders, Geoffrey
Data Structures and Algorithms
Discrete Mathematics
Machine Learning
Finding a minimum spanning tree (MST) for $n$ points in an arbitrary metric space is a fundamental primitive for hierarchical clustering and many other ML tasks, but this takes $Ω(n^2)$ time to even approximate. We introduce a framework for metric MSTs that first (1) finds a forest of disconnected components using practical heuristics, and then (2) finds a small weight set of edges to connect disjoint components of the forest into a spanning tree. We prove that optimally solving the second step still takes $Ω(n^2)$ time, but we provide a subquadratic 2.62-approximation algorithm. In the spirit of learning-augmented algorithms, we then show that if the forest found in step (1) overlaps with an optimal MST, we can approximate the original MST problem in subquadratic time, where the approximation factor depends on a measure of overlap. In practice, we find nearly optimal spanning trees for a wide range of metrics, while being orders of magnitude faster than exact algorithms.
title Approximate Tree Completion and Learning-Augmented Algorithms for Metric Minimum Spanning Trees
topic Data Structures and Algorithms
Discrete Mathematics
Machine Learning
url https://arxiv.org/abs/2502.12993