English

The average size of independent sets of graphs

Combinatorics 2018-07-24 v1

Abstract

In this paper, we study the average size of independent (vertex) sets of a graph. This invariant can be regarded as the logarithmic derivative of the independence polynomial evaluated at 11. We are specifically concerned with extremal questions. The maximum and minimum for general graphs are attained by the empty and complete graph respectively, while for trees we prove that the path minimises the average size of independent sets and the star maximises it. While removing a vertex does not always decrease the average size of independent sets, we prove that there always exists a vertex for which this is the case.

Keywords

Cite

@article{arxiv.1807.08290,
  title  = {The average size of independent sets of graphs},
  author = {Eric O. D. Andriantiana and Valisoa Razanajatovo Misanantenaina and Stephan Wagner},
  journal= {arXiv preprint arXiv:1807.08290},
  year   = {2018}
}