Stratified Morse Theory for Cell Complexes

Fuente: arXiv
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Main Authors: Nanda, Vidit, Tombari, Francesca
Format: Preprint
Published: 2026
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author Nanda, Vidit
Tombari, Francesca
author_facet Nanda, Vidit
Tombari, Francesca
contents We develop a version of discrete Morse theory for finite regular CW complexes equipped with an auxiliary stratification. The key construction is the halo of a cell, which contains all those faces in the boundary that enter closed sublevelsets precisely when the threshold reaches that cell's value. The complement of this halo in the boundary, called the shadow, is always a subcomplex. A stratified discrete Morse function requires Forman's conditions on each stratum together with the requirement that closures of paired cells admit filtered collapses onto their shadows. We establish fundamental Morse lemmas: filtered collapses across regular intervals, and controlled attachments at critical values. For functions satisfying only the stratum-wise Forman condition, we construct an upper envelope on the barycentric subdivision whose local Morse data decomposes into horizontal and vertical components. This yields a simplicial analogue of the standard tangential-normal splitting of local Morse data in the sense of Goresky and MacPherson.
format Preprint
id arxiv_https___arxiv_org_abs_2601_18343
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Stratified Morse Theory for Cell Complexes
Nanda, Vidit
Tombari, Francesca
Algebraic Topology
We develop a version of discrete Morse theory for finite regular CW complexes equipped with an auxiliary stratification. The key construction is the halo of a cell, which contains all those faces in the boundary that enter closed sublevelsets precisely when the threshold reaches that cell's value. The complement of this halo in the boundary, called the shadow, is always a subcomplex. A stratified discrete Morse function requires Forman's conditions on each stratum together with the requirement that closures of paired cells admit filtered collapses onto their shadows. We establish fundamental Morse lemmas: filtered collapses across regular intervals, and controlled attachments at critical values. For functions satisfying only the stratum-wise Forman condition, we construct an upper envelope on the barycentric subdivision whose local Morse data decomposes into horizontal and vertical components. This yields a simplicial analogue of the standard tangential-normal splitting of local Morse data in the sense of Goresky and MacPherson.
title Stratified Morse Theory for Cell Complexes
topic Algebraic Topology
url https://arxiv.org/abs/2601.18343