English

Pathographs and some (un)decidability results

Combinatorics 2025-05-27 v1 Discrete Mathematics Data Structures and Algorithms

Abstract

We introduce pathographs as a framework to study graph classes defined by forbidden structures, including forbidding induced subgraphs, minors, etc. Pathographs approximately generalize s-graphs of L\'ev\^eque--Lin--Maffray--Trotignon by the addition of two extra adjacency relations: one between subdivisible edges and vertices called spokes, and one between pairs of subdivisible edges called rungs. We consider the following decision problem: given a pathograph H\mathfrak{H} and a finite set of pathographs F\mathcal{F}, is there an F\mathcal{F}-free realization of H\mathfrak{H}? This may be regarded as a generalization of the "graph class containment problem": given two graph classes SS and SS', is it the case that SSS\subseteq S'? We prove the pathograph realization problem is undecidable in general, but it is decidable in the case that H\mathfrak{H} has no rungs (but may have spokes), or if F\mathcal{F} is closed under adding edges, spokes, and rungs. We also discuss some potential applications to proving decomposition theorems.

Keywords

Cite

@article{arxiv.2505.19871,
  title  = {Pathographs and some (un)decidability results},
  author = {Daniel Carter and Nicolas Trotignon},
  journal= {arXiv preprint arXiv:2505.19871},
  year   = {2025}
}

Comments

30 pages, 13 figures

R2 v1 2026-07-01T02:39:17.629Z