English

The Brown-Colbourn conjecture on zeros of reliability polynomials is false

Combinatorics 2007-05-23 v2 Statistical Mechanics Mathematical Physics math.MP

Abstract

We give counterexamples to the Brown-Colbourn conjecture on reliability polynomials, in both its univariate and multivariate forms. The multivariate Brown-Colbourn conjecture is false already for the complete graph K_4. The univariate Brown-Colbourn conjecture is false for certain simple planar graphs obtained from K_4 by parallel and series expansion of edges. We show, in fact, that a graph has the multivariate Brown-Colbourn property if and only if it is series-parallel.

Keywords

Cite

@article{arxiv.math/0301199,
  title  = {The Brown-Colbourn conjecture on zeros of reliability polynomials is false},
  author = {Gordon Royle and Alan D. Sokal},
  journal= {arXiv preprint arXiv:math/0301199},
  year   = {2007}
}

Comments

LaTeX2e, 17 pages. Version 2 makes a few small improvements in the exposition. To appear in Journal of Combinatorial Theory B

R2 v1 2026-07-22T16:51:14.361Z