Hardness Results for Laplacians of Simplicial Complexes via Sparse-Linear Equation Complete Gadgets


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Date

2022

Publication Type

Conference Paper

ETH Bibliography

yes

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Data

Abstract

We study linear equations in combinatorial Laplacians of k-dimensional simplicial complexes (kcomplexes), a natural generalization of graph Laplacians. Combinatorial Laplacians play a crucial role in homology and are a central tool in topology. Beyond this, they have various applications in data analysis and physical modeling problems. It is known that nearly-linear time solvers exist for graph Laplacians. However, nearly-linear time solvers for combinatorial Laplacians are only known for restricted classes of complexes. This paper shows that linear equations in combinatorial Laplacians of 2-complexes are as hard to solve as general linear equations. More precisely, for any constant c ≥ 1, if we can solve linear equations in combinatorial Laplacians of 2-complexes up to high accuracy in time Õ((# of nonzero coefficients)c), then we can solve general linear equations with polynomially bounded integer coefficients and condition numbers up to high accuracy in time Õ((# of nonzero coefficients)c). We prove this by a nearly-linear time reduction from general linear equations to combinatorial Laplacians of 2-complexes. Our reduction preserves the sparsity of the problem instances up to poly-logarithmic factors.

Publication status

published

Book title

49th EATCS International Conference on Automata, Languages, and Programming

Volume

229

Pages / Article No.

53

Publisher

Schloss Dagstuhl – Leibniz-Zentrum für Informatik

Event

49th International Colloquium on Automata, Languages, and Programming (ICALP 2022)

Edition / version

Methods

Software

Geographic location

Date collected

Date created

Subject

Simplicial Complexes; Combinatorial Laplacians; Linear Equations; Fine-Grained Complexity

Organisational unit

09687 - Kyng, Rasmus / Kyng, Rasmus check_circle

Notes

Funding

204787 - Algorithms and complexity for high-accuracy flows and convex optimization (SNF)

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