4K_1 free graphs on 13 vertices have cop number at most 2
Combinatorics
2026-01-15 v2
Abstract
The game of cops and robber has been studied for many years. Denoting to be the family of all graphs that contain no induced subgraph isomorphic to (e.g., with independence number less than ), we prove that for any , we have , where is the cop number. This improves a lower bound of a question proposed by Char et al. in a recent paper (arxiv, 2025), that any counterexample of a conjecture raised by Turcotte (2022) when must have at least 14 vertices.
Keywords
Cite
@article{arxiv.2601.00917,
title = {4K_1 free graphs on 13 vertices have cop number at most 2},
author = {Zhaoyu Wu},
journal= {arXiv preprint arXiv:2601.00917},
year = {2026}
}