Some conjectures on $r$-graphs and equivalences
Abstract
An -regular graph is an -graph, if every odd set of vertices is connected to its complement by at least edges. Seymour [On multicolourings of cubic graphs, and conjectures of Fulkerson and Tutte.~\emph{Proc.~London Math.~Soc.}~(3), 38(3): 423-460, 1979] conjectured (1) that every planar -graph is -edge colorable and (2) that every -graph has perfect matchings such that every edge is contained in precisely two of them. We study several variants of these conjectures. A -PM is a multiset of perfect matchings of an -graph such that every edge is in precisely of them. We show that the following statements are equivalent for every : 1. Every planar -graph has a -PM. 2. Every -minor-free -graph has a -PM. 3. Every -minor-free -graph has a -PM. 4. Every -graph whose underlying simple graph has crossing number at most has a -PM.
Cite
@article{arxiv.2411.01753,
title = {Some conjectures on $r$-graphs and equivalences},
author = {Yulai Ma and Eckhard Steffen and Isaak H. Wolf and Junxue Zhang},
journal= {arXiv preprint arXiv:2411.01753},
year = {2026}
}
Comments
11 pages, 1 figure. Minor typos corrected