# Graphs that contain multiply transitive matchings

## TL;DR

This paper studies special matchings in symmetric graphs, providing constructions, bounds on degree, and classifications for graphs with permutable and 2-transitive matchings, advancing understanding of graph symmetry properties.

## Contribution

It introduces new constructions and classifications of graphs with permutable and 2-transitive matchings, especially for large matchings and arc-transitive graphs.

## Key findings

- Graphs with permutable m-matchings have degree at least m when m ≥ 4.
- Characterization of locally primitive, arc-transitive graphs with permutable m-matchings for large m.
- Complete classification of graphs with 2-transitive and permutable perfect matchings.

## Abstract

Let $\Gamma$ be a finite, undirected, connected, simple graph. We say that a matching $\mathcal{M}$ is a \textit{permutable $m$-matching} if $\mathcal{M}$ contains $m$ edges and the subgroup of $\text{Aut}(\Gamma)$ that fixes the matching $\mathcal{M}$ setwise allows the edges of $\mathcal{M}$ to be permuted in any fashion. A matching $\mathcal{M}$ is \textit{2-transitive} if the setwise stabilizer of $\mathcal{M}$ in $\text{Aut}(\Gamma)$ can map any ordered pair of distinct edges of $\mathcal{M}$ to any other ordered pair of distinct edges of $\mathcal{M}$. We provide constructions of graphs with a permutable matching; we show that, if $\Gamma$ is an arc-transitive graph that contains a permutable $m$-matching for $m \ge 4$, then the degree of $\Gamma$ is at least $m$; and, when $m$ is sufficiently large, we characterize the locally primitive, arc-transitive graphs of degree $m$ that contain a permutable $m$-matching. Finally, we classify the graphs that have a $2$-transitive perfect matching and also classify graphs that have a permutable perfect matching.