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Main Authors: Beck, Matthias, Klivans, Caroline, Ross, Dustin
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2604.15253
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author Beck, Matthias
Klivans, Caroline
Ross, Dustin
author_facet Beck, Matthias
Klivans, Caroline
Ross, Dustin
contents Brion's Formula realizes the Laurent polynomial of lattice points in a lattice polytope P as the sum of rational functions associated to the vertices of P. In this paper, we consider the special case where P is a generalized permutohedron. We study a modification of the rational functions associated to the vertices of P depending on a given matroid M. Upon summing these rational functions, we describe how the resulting Laurent polynomial Q_M(P) behaves in certain ways like the lattice points of P, exhibiting natural recursive and reciprocity behaviors. Furthermore, upon evaluating Q_M(P) at 1, we recover the matroid Euler characteristic of Larson, Li, Payne, and Proudfoot, so the combinatorial approach in this paper gives new insight into studying these quantities.
format Preprint
id arxiv_https___arxiv_org_abs_2604_15253
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A matroidal twist on a formula of Brion
Beck, Matthias
Klivans, Caroline
Ross, Dustin
Combinatorics
Brion's Formula realizes the Laurent polynomial of lattice points in a lattice polytope P as the sum of rational functions associated to the vertices of P. In this paper, we consider the special case where P is a generalized permutohedron. We study a modification of the rational functions associated to the vertices of P depending on a given matroid M. Upon summing these rational functions, we describe how the resulting Laurent polynomial Q_M(P) behaves in certain ways like the lattice points of P, exhibiting natural recursive and reciprocity behaviors. Furthermore, upon evaluating Q_M(P) at 1, we recover the matroid Euler characteristic of Larson, Li, Payne, and Proudfoot, so the combinatorial approach in this paper gives new insight into studying these quantities.
title A matroidal twist on a formula of Brion
topic Combinatorics
url https://arxiv.org/abs/2604.15253