English

A generalization of Bondy's pancyclicity theorem

Combinatorics 2023-02-27 v1

Abstract

The bipartite independence number of a graph GG, denoted as α~(G)\tilde\alpha(G), is the minimal number kk such that there exist positive integers aa and bb with a+b=k+1a+b=k+1 with the property that for any two sets A,BV(G)A,B\subseteq V(G) with A=a|A|=a and B=b|B|=b, there is an edge between AA and BB. McDiarmid and Yolov showed that if δ(G)α~(G)\delta(G)\geq\tilde \alpha(G) then GG is Hamiltonian, extending the famous theorem of Dirac which states that if δ(G)G/2\delta(G)\geq |G|/2 then GG is Hamiltonian. In 1973, Bondy showed that, unless GG is a complete bipartite graph, Dirac's Hamiltonicity condition also implies pancyclicity, i.e., existence of cycles of all the lengths from 33 up to nn. In this paper we show that δ(G)α~(G)\delta(G)\geq\tilde \alpha(G) implies that GG is pancyclic or that G=Kn2,n2G=K_{\frac{n}{2},\frac{n}{2}}, thus extending the result of McDiarmid and Yolov, and generalizing the classic theorem of Bondy.

Keywords

Cite

@article{arxiv.2302.12752,
  title  = {A generalization of Bondy's pancyclicity theorem},
  author = {Nemanja Draganić and David Munhá Correia and Benny Sudakov},
  journal= {arXiv preprint arXiv:2302.12752},
  year   = {2023}
}
R2 v1 2026-06-28T08:48:58.371Z