P. Seymour

collaborators

3 papers

math.CO2026

Minors of plane digraphs

Maria Chudnovsky, Paul Seymour

A digraph $H$ is a ``semi-strong minor'' of another, $G$ , if a subdivision of $H$ can be obtained from a subdigraph of $G$ by contracting strongly-connected subdigraphs to single v…

math.CO2024

Excluding sums of Kuratowski graphs

Neil Robertson, Paul Seymour

We prove that a graph does not contain as a minor a graph formed by 0-, 1-, 2- or 3-summing $k$ copies of $K_{5}$ or $K_{3, 3}$ , if and only if it has bounded genus.

math.CO2024

Excluding disjoint Kuratowski graphs

Neil Robertson, Paul Seymour

A graph is a `` $k$ -Kuratowski graph'' if it has exactly $k$ components, each isomorphic to $K_{5}$ or to $K_{3, 3}$ . We prove that if a graph $G$ contains no $k$ -Kuratowski graph as a…