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In this paper, we prove that the Chow ring and augmented Chow ring of a matroid are equivariantly $\gamma$-positive under the action of any group of automorphisms. Our approach provides an explicit combinatorial interpretation of the…

Combinatorics · Mathematics 2026-05-05 Hsin-Chieh Liao

We introduce toric arrangements, essentially finite families of codimension 1 subtori of a torus or of their cosets, as a periodic generalization of hyperplane arrangements, compute cohomology of the complement of such an arrangement and…

Algebraic Geometry · Mathematics 2007-05-23 C. De Concini , C. Procesi

In the paper [Proceedings of the Japan Academy, Ser. A Mathematical Sciences, 95(10) 111-113], the authors introduce the concept of the Tutte polynomials of genus $g$ and announce that each matroid $M$ can be reconstructed from its Tutte…

Combinatorics · Mathematics 2024-02-13 Tsuyoshi Miezaki , Manabu Oura , Tadashi Sakuma , Hidehiro Shinohara

The Chow polynomial of a matroid is a fundamental invariant whose coefficients exhibit strong positivity properties, including $\gamma$-positivity. We interpret the normalized Chow coefficients as a probability distribution and establish…

Combinatorics · Mathematics 2026-04-30 Ronnie Cheng , Wangyang Lin

Associated to any graph is a toric ideal whose generators record relations among the cuts of the graph. We study these ideals and the geometry of the corresponding toric varieties. Our theorems and conjectures relate the combinatorial…

Commutative Algebra · Mathematics 2007-05-23 Bernd Sturmfels , Seth Sullivant

We discuss several extension properties of matroids and polymatroids and their application as necessary conditions for the existence of different matroid representations, namely linear, folded linear, algebraic, and entropic…

Combinatorics · Mathematics 2025-02-24 Michael Bamiloshin , Oriol Farràs , Carles Padró

The multivariate Tutte polynomial $\hat Z_M$ of a matroid $M$ is a generalization of the standard two-variable version, obtained by assigning a separate variable $v_e$ to each element $e$ of the ground set $E$. It encodes the full structure…

Combinatorics · Mathematics 2012-05-25 Adam Bohn , Peter J. Cameron , Peter Müller

We provide a natural definition of an elliptic arrangement, extending the classical framework to an elliptic curve E with complex multiplication. We analyse the intersections of elements of the arrangement and their connected components as…

Combinatorics · Mathematics 2026-05-13 Luca Moci , Roberto Pagaria , Maddalena Pismataro , Alejandro Vargas

We illuminate the relation between the Bruhat order on the symmetric group and structure constants (Littlewood-Richardson coefficients) for the cohomology of the flag manifold in terms of its basis of Schubert classes. Equivalently, the…

alg-geom · Mathematics 2016-11-08 Nantel Bergeron , Frank Sottile

Zonotopal algebra deals with ideals and vector spaces of polynomials that are related to several combinatorial and geometric structures defined by a finite sequence of vectors. Given such a sequence X, an integer k>=-1 and an upper set in…

Combinatorics · Mathematics 2015-03-17 Matthias Lenz

Blasiak verified a conjecture of White for graphic matroids by showing that the toric ideal of a graphic matroid is generated by quadrics. In this paper, we extend this result to frame matroids satisfying a linearity condition. Such classes…

Combinatorics · Mathematics 2020-04-10 Sean McGuinness

We define Chern numbers of a matroid. These numbers are obtained when intersecting appropriate matroid Chern-Schwartz-MacPherson cycles defined by L\'opez de Medrano, Rinc\'on, and Shaw. We prove that when a matroid arises from a complex…

Combinatorics · Mathematics 2023-10-18 Eline Mannino

We introduce a new class of matroids, called graph curve matroids. A graph curve matroid is associated to a graph and defined on the vertices of the graph as a ground set. We prove that these matroids provide a combinatorial description of…

Combinatorics · Mathematics 2024-08-06 Alheydis Geiger , Kevin Kuehn , Raluca Vlad

We introduce a new matroid width parameter based on the operation of matroid amalgamation, which we call amalgam-width. The parameter is linearly related to branch-width on finitely representable matroids (which is not possible for…

Discrete Mathematics · Computer Science 2013-06-11 Lukas Mach , Tomas Toufar

We show that f-vectors of matroid complexes of realisable matroids are log-concave. This was conjectured by Mason in 1972. Our proof uses the recent result by Huh and Katz who showed that the coefficients of the characteristic polynomial of…

Combinatorics · Mathematics 2013-06-11 Matthias Lenz

In this paper, we introduce the terminology of matroids into the study of Zariski-pairs related to rational elliptic surfaces, aiming to simplify the presentation and arguments involved. As an application, we provide new examples of Zariski…

Algebraic Geometry · Mathematics 2019-02-14 Ryutaro Sato , Shinzo Bannai

Applications of algebraic geometry have sparked much recent work on algebraic matroids. An algebraic matroid encodes algebraic dependencies among coordinate functions on a variety. We study the behavior of algebraic matroids under joins and…

Combinatorics · Mathematics 2026-05-15 Fatemeh Mohammadi , Jessica Sidman , Louis Theran

This chapter combines an introduction and research survey about Schubert varieties. The theme is to combinatorially classify their singularities using a family of polynomial ideals generated by determinants.

Algebraic Geometry · Mathematics 2023-03-03 Alexander Woo , Alexander Yong

A theorem of Mandel allows to determine the covector set of an oriented matroid from its set of topes by using the composition condition. We provide a generalization of that result, stating that the covector set of a conditional oriented…

Combinatorics · Mathematics 2023-09-20 Hery Randriamaro

We develop a multigraded variant of Castelnuovo-Mumford regularity. Motivated by toric geometry, we work with modules over a polynomial ring graded by a finitely generated abelian group. As in the standard graded case, our definition of…

Commutative Algebra · Mathematics 2010-03-15 Diane Maclagan , Gregory G. Smith