English

Counterexamples to two conjectures about matroids

Combinatorics 2026-07-02 v1

Abstract

We give counterexamples to two well-known conjectures about matroids: White's conjecture on the generation of the toric ideal by symmetric exchange binomials, and a conjecture of Mason on the log-concavity of the counts of flats of a given rank.

Cite

@article{arxiv.2607.02208,
  title  = {Counterexamples to two conjectures about matroids},
  author = {Matt Larson},
  journal= {arXiv preprint arXiv:2607.02208},
  year   = {2026}
}