The Merino-Welsh Conjecture holds for Series-Parallel Graphs
arXiv:1303.6416
Abstract
The Merino-Welsh conjecture asserts that the number of spanning trees of a graph is no greater than the maximum of the numbers of totally cyclic orientations and acyclic orientations of that graph. We prove this conjecture for the class of series-parallel graphs.
12 pages, includes Mathematica code in Appendix