Combinatorial Laplacians and Relative Homology of Complex Pairs

Fuente: arXiv
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Main Authors: Zhan, Xiongfeng, Huang, Xueyi, Lu, Lu
Format: Preprint
Published: 2025
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author Zhan, Xiongfeng
Huang, Xueyi
Lu, Lu
author_facet Zhan, Xiongfeng
Huang, Xueyi
Lu, Lu
contents As a discretization of the Hodge Laplacian, the combinatorial Laplacian of simplicial complexes has garnered significant attention. In this paper, we study combinatorial Laplacians for complex pairs $(X, A)$, where $A$ is a subcomplex of a simplicial complex $X$. We establish a relative version of the matrix-tree theorem for complex pairs, which generalizes both the matrix-tree theorem for simplicial complexes proved by Duval, Klivans, and Martin (2009) and the result for Dirichlet eigenvalues of graph pairs by Chung (1996). Furthermore, we derive several lower bounds for the spectral gaps of complex pairs and characterize the equality case for one sharp lower bound. As by-products, we obtain sufficient conditions for the vanishing of relative homology. Our results demonstrate that the combinatorial Laplacians for complex pairs are closely related to relative homology.
format Preprint
id arxiv_https___arxiv_org_abs_2507_16381
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Combinatorial Laplacians and Relative Homology of Complex Pairs
Zhan, Xiongfeng
Huang, Xueyi
Lu, Lu
Combinatorics
Algebraic Topology
05E45, 55U10
As a discretization of the Hodge Laplacian, the combinatorial Laplacian of simplicial complexes has garnered significant attention. In this paper, we study combinatorial Laplacians for complex pairs $(X, A)$, where $A$ is a subcomplex of a simplicial complex $X$. We establish a relative version of the matrix-tree theorem for complex pairs, which generalizes both the matrix-tree theorem for simplicial complexes proved by Duval, Klivans, and Martin (2009) and the result for Dirichlet eigenvalues of graph pairs by Chung (1996). Furthermore, we derive several lower bounds for the spectral gaps of complex pairs and characterize the equality case for one sharp lower bound. As by-products, we obtain sufficient conditions for the vanishing of relative homology. Our results demonstrate that the combinatorial Laplacians for complex pairs are closely related to relative homology.
title Combinatorial Laplacians and Relative Homology of Complex Pairs
topic Combinatorics
Algebraic Topology
05E45, 55U10
url https://arxiv.org/abs/2507.16381