ETH-Tight Complexity of Optimal Morse Matching on Bounded-Treewidth Complexes

Fuente: arXiv
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Autores principales: Philip, Geevarghese, Vågset, Erlend Raa
Formato: Preprint
Publicado: 2026
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author Philip, Geevarghese
Vågset, Erlend Raa
author_facet Philip, Geevarghese
Vågset, Erlend Raa
contents The Optimal Morse Matching (OMM) problem asks for a discrete gradient vector field on a simplicial complex that minimizes the number of critical simplices. It is NP-hard and has been studied extensively in heuristic, approximation, and parameterized complexity settings. Parameterized by treewidth $k$, OMM has long been known to be solvable on triangulations of $3$-manifolds in $2^{O(k^2)} n^{O(1)}$ time and in FPT time for triangulations of arbitrary manifolds, but the exact dependence on $k$ has remained an open question. We resolve this by giving a new $2^{O(k \log k)} n$-time algorithm for any finite regular CW complex, and show that no $2^{o(k \log k)} n^{O(1)}$-time algorithm exists unless the Exponential Time Hypothesis (ETH) fails.
format Preprint
id arxiv_https___arxiv_org_abs_2603_05406
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle ETH-Tight Complexity of Optimal Morse Matching on Bounded-Treewidth Complexes
Philip, Geevarghese
Vågset, Erlend Raa
Computational Geometry
Computational Complexity
Discrete Mathematics
Data Structures and Algorithms
General Topology
68Q27 (Primary) 68Q25, 68Q17, 05C85, 57Q05 (Secondary)
F.2.2; G.2.2; I.3.5; F.1.3
The Optimal Morse Matching (OMM) problem asks for a discrete gradient vector field on a simplicial complex that minimizes the number of critical simplices. It is NP-hard and has been studied extensively in heuristic, approximation, and parameterized complexity settings. Parameterized by treewidth $k$, OMM has long been known to be solvable on triangulations of $3$-manifolds in $2^{O(k^2)} n^{O(1)}$ time and in FPT time for triangulations of arbitrary manifolds, but the exact dependence on $k$ has remained an open question. We resolve this by giving a new $2^{O(k \log k)} n$-time algorithm for any finite regular CW complex, and show that no $2^{o(k \log k)} n^{O(1)}$-time algorithm exists unless the Exponential Time Hypothesis (ETH) fails.
title ETH-Tight Complexity of Optimal Morse Matching on Bounded-Treewidth Complexes
topic Computational Geometry
Computational Complexity
Discrete Mathematics
Data Structures and Algorithms
General Topology
68Q27 (Primary) 68Q25, 68Q17, 05C85, 57Q05 (Secondary)
F.2.2; G.2.2; I.3.5; F.1.3
url https://arxiv.org/abs/2603.05406