English

Sharp estimates for spanning trees

Combinatorics 2022-04-14 v4

Abstract

We prove the following sharp estimate for the number of spanning trees of a graph in terms of its vertex-degrees: a simple graph GG on nn vertices has at most (1/n2)vV(G)(d(v)+1)(1/n^{2}) \prod_{v \in V(G)} (d(v)+1) spanning trees. This result is tight (for complete graphs), and improves earlier estimates of Alon from 1990 and Kostochka from 1995 by a factor of about 1/n1/n (for dense graphs). We additionally show that an analogous bound holds for the weighted spanning tree enumerator of a (nonnegatively) weighted graph as well.

Keywords

Cite

@article{arxiv.2102.01669,
  title  = {Sharp estimates for spanning trees},
  author = {Steven Klee and Bhargav Narayanan and Lisa Sauermann},
  journal= {arXiv preprint arXiv:2102.01669},
  year   = {2022}
}

Comments

It has been pointed out to us when this paper was under review that the results are not new; in fact a stronger bound was proved by Grone and Merris [Discrete Math. 69 (1988), 97-99]