Borsuk-Ulam property for graphs

TL;DR

This paper characterizes when the Borsuk-Ulam property holds for maps between finite graphs with involution, using graph braid groups and discrete Morse theory to analyze homotopy classes.

Contribution

It provides a characterization of homotopy classes satisfying the Borsuk-Ulam property for graphs with involution, employing graph braid groups and discrete Morse theory.

Findings

Characterization of homotopy classes with the Borsuk-Ulam property

Use of graph braid groups to analyze homotopy classes

Application of discrete Morse theory in the analysis

Abstract

For finite connected graphs $\Gamma$ and $G$, with $\Gamma$ admitting a free involution $\tau$, we characterize the based homotopy classes $\alpha\in[\Gamma,G]$ for which the Borsuk-Ulam property holds in the sense of Gon\c{c}alves, Guaschi and Casteluber-Laass, i.e., the homotopy classes $\alpha$ so that each of its representatives $f\in\alpha$ satisfies $f(x) = f(\tau\cdot x)$ for some $x\in\Gamma$. This is attained through a graph-braid-group perspective aided by the use of discrete Morse theory.