English

Bergeron's conjecture & a tale of two binomial coefficients

Combinatorics 2026-07-04 v1

Abstract

Bergeron's conjecture states that, if 1a<b<c<d1\leq a<b<c<d are integers with ad=bcad=bc, then one has the coefficient-wise inequality (b+cb)q(a+da)q{\binom{b+c}b}_q \ge {\binom{a+d}a}_q among two Gaussian polynomials. It originated in algebraic combinatorics and is wide open. The corresponding inequality for binomial coefficients (i.e., the case q=1q=1) must be known to experts, but we could not find it in the literature. We give two proofs, each generalizing the statement in a separate direction. Binomial coefficients (and Gaussian polynomials) are fundamental combinatorial objects, and so one naturally hopes to see a combinatorial proof of this inequality. However, this seems hard to come by. We nevertheless give a combinatorial proof of a special case.

Keywords

Cite

@article{arxiv.2607.04050,
  title  = {Bergeron's conjecture & a tale of two binomial coefficients},
  author = {Tewodros Amdeberhan and Matthias Beck},
  journal= {arXiv preprint arXiv:2607.04050},
  year   = {2026}
}

Comments

8 pages