Siblings of countable cographs
Combinatorics
2020-04-28 v1
Abstract
We show that every countable cograph has either one or infinitely many siblings. This answers, very partially, a conjecture of Thomass\'e. The main tools are the notion of well quasi ordering and the correspondence between cographs and some labelled ordered trees.
Keywords
Cite
@article{arxiv.2004.12457,
title = {Siblings of countable cographs},
author = {Gena Hahn and Maurice Pouzet and Robert Woodrow},
journal= {arXiv preprint arXiv:2004.12457},
year = {2020}
}
Comments
Dedicated to the memory of Ivo G. Rosenberg, Three figures, 27 pages