Group Connectivity under $3$-Edge-Connectivity

TL;DR

This paper investigates the relationship between group connectivity properties in 3-edge-connected graphs, extending previous results and characterizing when different groups yield equivalent connectivity, especially addressing open problems in the field.

Contribution

It extends the understanding of group connectivity equivalences in 3-edge-connected graphs, resolving open questions and characterizing all such group pairs.

Findings

Every 3-edge-connected S-connected graph is T-connected if and only if nd Tre not nd .

The result generalizes previous findings from 2-edge-connected graphs to 3-edge-connected graphs.

It provides a complete characterization of group connectivity equivalence under 3-edge-connectivity.

Abstract

Let $S,T$ be two distinct finite Abelian groups with $|S|=|T|$. A fundamental theorem of Tutte shows that a graph admits a nowhere-zero $S$-flow if and only if it admits a nowhere-zero $T$-flow. Jaeger, Linial, Payan and Tarsi in 1992 introduced group connectivity as an extension of flow theory, and they asked whether such a relation holds for group connectivity analogy. It was negatively answered by Hu\v{s}ek, Moheln\'{i}kov\'{a} and \v{S}\'{a}mal in 2017 for graphs with edge-connectivity 2 for the groups $S=\mathbb{Z}_4$ and $T=\mathbb{Z}_2^2$. In this paper, we extend their results to $3$-edge-connected graphs (including both cubic and general graphs), which answers open problems proposed by Hu\v{s}ek, Moheln\'{i}kov\'{a} and \v{S}\'{a}mal(2017) and Lai, Li, Shao and Zhan(2011). Combining some previous results, this characterizes all the equivalence of group connectivity under $3$-edge-connectivity, showing that every $3$-edge-connected $S$-connected graph is $T$-connected if and only if $\{S,T\}\neq \{\mathbb{Z}_4,\mathbb{Z}_2^2\}$.