English

Graphs with Many Hamiltonian Paths

Combinatorics 2025-07-30 v3

Abstract

A graph is \emph{hamiltonian-connected} if every pair of vertices can be connected by a hamiltonian path, and it is \emph{hamiltonian} if it contains a hamiltonian cycle. We construct families of non-hamiltonian graphs for which the ratio of pairs of vertices connected by hamiltonian paths to all pairs of vertices approaches 1. We then consider minimal graphs that are hamiltonian-connected. It is known that any order-nn graph that is hamiltonian-connected must have 3n/2\geq 3n/2 edges. We construct an infinite family of graphs realizing this minimum.

Keywords

Cite

@article{arxiv.2106.13372,
  title  = {Graphs with Many Hamiltonian Paths},
  author = {Erik Carlson and Willem Fletcher and MurphyKate Montee and Chi Nguyen and Jarne Renders and Xingyi Zhang},
  journal= {arXiv preprint arXiv:2106.13372},
  year   = {2025}
}

Comments

v3: substantial re-writing, including new author. To appear in Involve. v2: 12 pages, 6 figures. Substantial re-write including new results and removing results already proven by others. v1: 16 pages, 7 figures

R2 v1 2026-06-24T03:34:56.625Z