A Simple Deterministic Reduction From Gomory-Hu Tree to Maxflow and Expander Decomposition

Fuente: arXiv
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Main Authors: Gutenberg, Maximilian Probst, Yuan, Weixuan
Format: Preprint
Published: 2025
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author Gutenberg, Maximilian Probst
Yuan, Weixuan
author_facet Gutenberg, Maximilian Probst
Yuan, Weixuan
contents Given an undirected graph $G=(V,E,w)$, a Gomory-Hu tree $T$ (Gomory and Hu, 1961) is a tree on $V$ that preserves all-pairs mincuts of $G$ exactly. We present a simple and efficient randomized reduction from Gomory-Hu trees to polylog maxflow computations. On unweighted graphs, our reduction reduces to maxflow computations on graphs of total instance size $\tilde{O}(m)$ and the algorithm requires only $\tilde{O}(m)$ additional time. Our reduction is the first that is tight up to polylog factors. The reduction also seamlessly extends to weighted graphs, however, instance sizes and runtime increase to $\tilde{O}(n^2)$. Finally, we show how to extend our reduction to reduce Gomory-Hu trees for unweighted hypergraphs to maxflow in hypergraphs. Again, our reduction is the first that is tight up to polylog factors.
format Preprint
id arxiv_https___arxiv_org_abs_2510_27330
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Simple Deterministic Reduction From Gomory-Hu Tree to Maxflow and Expander Decomposition
Gutenberg, Maximilian Probst
Yuan, Weixuan
Data Structures and Algorithms
Given an undirected graph $G=(V,E,w)$, a Gomory-Hu tree $T$ (Gomory and Hu, 1961) is a tree on $V$ that preserves all-pairs mincuts of $G$ exactly. We present a simple and efficient randomized reduction from Gomory-Hu trees to polylog maxflow computations. On unweighted graphs, our reduction reduces to maxflow computations on graphs of total instance size $\tilde{O}(m)$ and the algorithm requires only $\tilde{O}(m)$ additional time. Our reduction is the first that is tight up to polylog factors. The reduction also seamlessly extends to weighted graphs, however, instance sizes and runtime increase to $\tilde{O}(n^2)$. Finally, we show how to extend our reduction to reduce Gomory-Hu trees for unweighted hypergraphs to maxflow in hypergraphs. Again, our reduction is the first that is tight up to polylog factors.
title A Simple Deterministic Reduction From Gomory-Hu Tree to Maxflow and Expander Decomposition
topic Data Structures and Algorithms
url https://arxiv.org/abs/2510.27330