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Bibliographic Details
Main Author: Usher, Michael
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2512.24025
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author Usher, Michael
author_facet Usher, Michael
contents We develop the notion of a "filtered cospan" as an algebraic object that stands in the same relation to interlevel persistence modules as filtered chain complexes stand with respect to sublevel persistence modules. This relation is expressed via a functor from a category of filtered cospans to a category of persistence modules that arise in Bauer-Botnan-Fluhr's study of relative interlevel set homology. We associate a filtered cospan to a Morse function $f:X\to [-Λ,Λ]$ such that $\partial X$ is the union of the regular level sets $f^{-1}(\{\pmΛ\})$; this allows us to capture the interlevel persistence of such a function in terms of data associated to Morse chain complexes. Similar filtered cospans are associated to simplicial and singular chain complexes, and isomorphism theorems are proven relating these to each other and to relative interlevel set homology. Filtered cospans can be decomposed, under modest hypotheses, into certain standard elementary summands, giving rise to a notion of persistence diagram for filtered cospans that is amenable to computation. An isometry theorem connects interleavings of filtered cospans to matchings between these persistence diagrams.
format Preprint
id arxiv_https___arxiv_org_abs_2512_24025
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Filtered cospans and interlevel persistence with boundary conditions
Usher, Michael
Algebraic Topology
We develop the notion of a "filtered cospan" as an algebraic object that stands in the same relation to interlevel persistence modules as filtered chain complexes stand with respect to sublevel persistence modules. This relation is expressed via a functor from a category of filtered cospans to a category of persistence modules that arise in Bauer-Botnan-Fluhr's study of relative interlevel set homology. We associate a filtered cospan to a Morse function $f:X\to [-Λ,Λ]$ such that $\partial X$ is the union of the regular level sets $f^{-1}(\{\pmΛ\})$; this allows us to capture the interlevel persistence of such a function in terms of data associated to Morse chain complexes. Similar filtered cospans are associated to simplicial and singular chain complexes, and isomorphism theorems are proven relating these to each other and to relative interlevel set homology. Filtered cospans can be decomposed, under modest hypotheses, into certain standard elementary summands, giving rise to a notion of persistence diagram for filtered cospans that is amenable to computation. An isometry theorem connects interleavings of filtered cospans to matchings between these persistence diagrams.
title Filtered cospans and interlevel persistence with boundary conditions
topic Algebraic Topology
url https://arxiv.org/abs/2512.24025