A counterexample regarding labelled well-quasi-ordering
Combinatorics
2018-10-08 v3
Abstract
Korpelainen, Lozin, and Razgon conjectured that a hereditary property of graphs which is well-quasi-ordered by the induced subgraph order and defined by only finitely many minimal forbidden induced subgraphs is labelled well-quasi-ordered, a notion stronger than that of -well-quasi-order introduced by Pouzet in the 1970s. We present a counterexample to this conjecture. In fact, we exhibit a hereditary property of graphs which is well-quasi-ordered by the induced subgraph order and defined by finitely many minimal forbidden induced subgraphs yet is not -well-quasi-ordered. This counterexample is based on the widdershins spiral, which has received some study in the area of permutation patterns.
Keywords
Cite
@article{arxiv.1709.10042,
title = {A counterexample regarding labelled well-quasi-ordering},
author = {Robert Brignall and Michael Engen and Vincent Vatter},
journal= {arXiv preprint arXiv:1709.10042},
year = {2018}
}