English

2-factors in $\frac{3}{2}$-tough maximal planar graphs

Combinatorics 2025-07-02 v1

Abstract

The toughness of a graph GG is defined as the minimum value of S/c(GS)|S|/c(G-S) over all cutsets SS of GG if GG is noncomplete, and is defined to be \infty if GG is complete. For a real number tt, we say that GG is tt-tough if its toughness is at least tt. Followed from the classic 1956 result of Tutte, every more than 32\frac{3}{2}-tough planar graph on at least three vertices has a 2-factor. In 1999, Owens constructed a sequence of maximal planar graphs with toughness 32ε\frac{3}{2}-\varepsilon for any ε>0\varepsilon >0, but the graphs do not contain any 2-factor. He then posed the question of whether there exists a maximal planar graph with toughness exactly 32\frac{3}{2} and with no 2-factor. This question was recently answered affirmatively by the third author. This naturally leads to the question: under what conditions does a 32\frac{3}{2}-tough maximal planar graph contain a 2-factor? In this paper, we provide a sufficient condition for the existence of 2-factors in 32\frac{3}{2}-tough maximal planar graphs, stated as a bound on the distance between vertices of degree 3.

Keywords

Cite

@article{arxiv.2507.00395,
  title  = {2-factors in $\frac{3}{2}$-tough maximal planar graphs},
  author = {Lili Hao and Hui Ma and Songling Shan and Weihua Yang},
  journal= {arXiv preprint arXiv:2507.00395},
  year   = {2025}
}

Comments

arXiv admin note: text overlap with arXiv:2211.11714