English

Domination polynomial is unimodal for large graphs with a universal vertex

Combinatorics 2021-11-03 v2

Abstract

For a undirected simple graph GG, let di(G)d_i(G) be the number of ii-element dominating vertex set of GG. The domination polynomial of the graph GG is defined as D(G,x)=i=1ndi(G)xi.D(G, x) = \sum_{i = 1}^n d_i(G)x^i. Alikhani and Peng conjectured that D(G,x)D(G, x) is unimodal for any graph GG. Answering a proposal of Beaton and Brown, we show that D(G,x)D(G, x) is unimodal when GG has at least 2132^{13} vertices and has a universal vertex, which is a vertex adjacent to any other vertex of GG. We further determine possible locations of the mode.

Keywords

Cite

@article{arxiv.2111.00641,
  title  = {Domination polynomial is unimodal for large graphs with a universal vertex},
  author = {Shengtong Zhang},
  journal= {arXiv preprint arXiv:2111.00641},
  year   = {2021}
}

Comments

8 pages, no figures. Correct some typos and slightly strengthen results