English

Minor-Obstructions for Apex Sub-unicyclic Graphs

Combinatorics 2019-02-07 v1

Abstract

A graph is sub-unicyclic if it contains at most one cycle. We also say that a graph GG is kk-apex sub-unicyclic if it can become sub-unicyclic by removing kk of its vertices. We identify 29 graphs that are the minor-obstructions of the class of 11-apex sub-unicyclic graphs, i.e., the set of all minor minimal graphs that do not belong in this class. For bigger values of kk, we give an exact structural characterization of all the cactus graphs that are minor-obstructions of kk-apex sub-unicyclic graphs and we enumerate them. This implies that, for every kk, the class of kk-apex sub-unicyclic graphs has at least 0.34k2.5(6.278)k0.34\cdot k^{-2.5}(6.278)^{k} minor-obstructions.

Keywords

Cite

@article{arxiv.1902.02231,
  title  = {Minor-Obstructions for Apex Sub-unicyclic Graphs},
  author = {Alexandros Leivaditis and Alexandros Singh and Giannos Stamoulis and Dimitrios Thilikos and Konstantinos Tsatsanis and Vasiliki Velona},
  journal= {arXiv preprint arXiv:1902.02231},
  year   = {2019}
}
R2 v1 2026-06-23T07:33:42.059Z