Compatible Hamilton cycles in graphs with large minimum degree
Abstract
The renowned theorem of Dirac states that if is a graph with minimum degree at least then has a Hamilton cycle. A natural generalisation asks what properties of an edge-colouring of guarantee the existence of a properly edge-coloured Hamilton cycle in . This concept can be further generalised as follows: an \emph{incompatibility system} for is a set~ of `forbidden' pairs of adjacent edges, that is, . A cycle in is then \emph{compatible} if no two of its edges form a pair in . The system is called \emph{-bounded} if for all and , there are at most pairs . How small must be to guarantee the existence of a compatible Hamilton cycle in ? Krivelevich, Lee and Sudakov showed that suffices (for large), while an example of Bollob\'as and Erd\H{o}s shows that is necessary. We significantly reduce this gap for large graphs of minimum degree at least , by showing that suffices but is necessary for such graphs. In fact, we give more precise bounds which are functions of .
Cite
@article{arxiv.2603.21984,
title = {Compatible Hamilton cycles in graphs with large minimum degree},
author = {Natalie Behague and Francesco Di Braccio and Bertille Granet and Allan Lo},
journal= {arXiv preprint arXiv:2603.21984},
year = {2026}
}
Comments
23 pages