A Lower Bound on the Self-intersections of Fold Singularities

Fuente: arXiv
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Auteurs principaux: Drouin, Joshua, Kahmeyer, Liam
Format: Preprint
Publié: 2026
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_version_ 1866910215472939008
author Drouin, Joshua
Kahmeyer, Liam
author_facet Drouin, Joshua
Kahmeyer, Liam
contents For an oriented surface $S$, the singular set of a fold map $f:S\rightarrow \mathbb{R}^2$ is a collection of smooth curves, also known as fold singularities. We construct a sharp lower bound on the number of self-intersections of such fold singularities. This is done by first establishing a sharp lower bound on the number of self-intersections of the boundary of a surface immersed in $\mathbb{R}^2$. We then construct a sharp lower bound for the number of self-intersections of the singular set of a simple stable fold map of a surface to $\mathbb{R}^2$ by viewing the connected components of the singular set as the boundary components of smaller surface components, and invoking the previously constructed lower bound for the number of self-intersections of an immersed boundary.
format Preprint
id arxiv_https___arxiv_org_abs_2605_12989
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Lower Bound on the Self-intersections of Fold Singularities
Drouin, Joshua
Kahmeyer, Liam
Geometric Topology
57R45, 58K30, 57R42, 57K20
For an oriented surface $S$, the singular set of a fold map $f:S\rightarrow \mathbb{R}^2$ is a collection of smooth curves, also known as fold singularities. We construct a sharp lower bound on the number of self-intersections of such fold singularities. This is done by first establishing a sharp lower bound on the number of self-intersections of the boundary of a surface immersed in $\mathbb{R}^2$. We then construct a sharp lower bound for the number of self-intersections of the singular set of a simple stable fold map of a surface to $\mathbb{R}^2$ by viewing the connected components of the singular set as the boundary components of smaller surface components, and invoking the previously constructed lower bound for the number of self-intersections of an immersed boundary.
title A Lower Bound on the Self-intersections of Fold Singularities
topic Geometric Topology
57R45, 58K30, 57R42, 57K20
url https://arxiv.org/abs/2605.12989