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Postnikov gave a combinatorial description of the cells in a totally-nonnegative Grassmannian. These cells correspond to a special class of matroids called positroid. We prove his conjecture that a positroid is exactly an intersection of…

Combinatorics · Mathematics 2010-10-12 Suho Oh

We give a semi-small orthogonal decomposition of the Chow ring of a matroid M. The decomposition is used to give simple proofs of Poincar\'e duality, the hard Lefschetz theorem, and the Hodge-Riemann relations for the Chow ring, recovering…

Algebraic Geometry · Mathematics 2020-10-15 Tom Braden , June Huh , Jacob P. Matherne , Nicholas Proudfoot , Botong Wang

We provide explicit combinatorial formulas for the Chow polynomial and for the augmented Chow polynomial of uniform matroids, thereby proving a conjecture by Ferroni. These formulas refine existing formulas by Hampe and by Eur, Huh, and…

Combinatorics · Mathematics 2024-12-02 Elena Hoster

This paper is the third in a series that researches the Morse Theory, gradient flows, concavity and complexity on smooth compact manifolds with boundary. Employing the local analytic models from \cite{K2}, for \emph{traversally generic…

Geometric Topology · Mathematics 2014-08-11 Gabriel Katz

In this paper we shall generalize the chamber structure of polarizations defined by Qin, and as an application we shall compute the Picard groups of moduli spaces of stable sheaves on a non-rational ruled surface.

alg-geom · Mathematics 2016-08-14 Kōta Yoshioka

We introduce the notion of a quasi-matroidal class of ordered simplicial complexes: an approximation to the idea of a matroid cryptomorphism in the landscape of ordered simplicial complexes. A quasi-matroidal class contains pure shifted…

Combinatorics · Mathematics 2016-08-16 Jose Alejandro Samper

We prove the so-called master relation in the tautological ring of the moduli space of curves that implies polynomial properties of the Dubrovin-Zhang hierarchies associated to different versions of cohomological field theories as well as…

Algebraic Geometry · Mathematics 2025-04-07 Xavier Blot , Adrien Sauvaget , Sergey Shadrin

We study combinatorial inequalities for various classes of set systems: matroids, polymatroids, poset antimatroids, and interval greedoids. We prove log-concavity inequalities for counting certain weighted feasible words, which generalize…

Combinatorics · Mathematics 2024-08-01 Swee Hong Chan , Igor Pak

Naruki gave an explicit construction of the moduli space of marked cubic surfaces, starting from a toric variety and proceeding with blow ups and contractions. Using his result, we compute the Chow groups and the Chern classes of this…

Algebraic Geometry · Mathematics 2007-05-23 Elisabetta Colombo , Bert van Geemen

In this note we introduce a family of polynomials on a matroid derived from chain Tutte polynomials which generalize the classic and ubiquitous characteristic polynomial. We show that the coefficients of these polynomials alternate and…

Combinatorics · Mathematics 2025-08-08 Gary Lazzaro , Max Wakefield , Jason Weiss

We study paving matroids, their realization spaces, and their closures, along with matroid varieties and circuit varieties. Within this context, we introduce three distinct methods for generating polynomials within the associated ideals of…

Algebraic Geometry · Mathematics 2026-03-24 Emiliano Liwski , Fatemeh Mohammadi

Let $G$ be the product $GL_r(C) \times (C^\times)^n$. We show that the $G$-equivariant Chow class of a $G$ orbit closure in the space of $r$-by-$n$ matrices is determined by a matroid. To do this, we split the natural surjective map from…

Algebraic Geometry · Mathematics 2016-09-21 Andrew Berget , Alex Fink

The classical matrix tree theorem relates the number of spanning trees of a connected graph with the product of the nonzero eigenvalues of its Laplacian matrix. The class of regular matroids generalizes that of graphical matroids, and a…

Combinatorics · Mathematics 2014-05-12 Aaron Dall , Julian Pfeifle

Following the work of Gao and Xie in [2], we state some properties of the inverse Kazhdan-Lusztig polynomial of a matroid. We also give partial answers to a conjecture that states that regular connected matroids are non-degenerate. We link…

Combinatorics · Mathematics 2021-04-21 Lorenzo Vecchi

Motivated by the notion of the inverse $Z$-polynomial introduced by Ferroni, Matherne, Stevens, and Vecchi, we study the equivariant inverse $Z$-polynomial of a matroid equipped with a finite group. We prove that the coefficients of the…

Combinatorics · Mathematics 2026-01-27 Alice L. L. Gao , Yun Li , Matthew H. Y. Xie

June Huh and Matthew Stevens conjectured that the Hilbert-Poincar\'e series of the Chow ring of any matroid is a polynomial with only real zeros. We prove this conjecture for the class of uniform matroids. We also prove that the Chow…

Combinatorics · Mathematics 2025-09-19 Petter Brändén , Lorenzo Vecchi

We prove that for any monoid scheme M over a field with proper multiplication maps from M x M to M, we have a natural PD-structure on the ideal CH_{>0}(M) of CH(M) with regard to the Pontryagin ring structure. Further we investigate to what…

Algebraic Geometry · Mathematics 2009-04-28 Ben Moonen , Alexander Polishchuk

Let $M$ be a complete nonsingular fine moduli space of modules over an algebra $S$. A set of conditions is given for the Chow ring of $M$ to be generated by the Chern classes of certain universal bundles occurring in a projective resolution…

alg-geom · Mathematics 2008-02-03 A. D. King , Charles H. Walter

Huh-Stevens and Ferroni-Schr\"oter independently conjectured that Hilbert-Poincar\'e series of Chow rings of geometric lattices have only real zeros. Ferroni, Matherne and the second author extended this conjecture to Chow polynomials of…

Combinatorics · Mathematics 2025-11-11 Petter Brändén , Lorenzo Vecchi

We associate to every matroid M a polynomial with integer coefficients, which we call the Kazhdan-Lusztig polynomial of M, in analogy with Kazhdan-Lusztig polynomials in representation theory. We conjecture that the coefficients are always…

Combinatorics · Mathematics 2016-07-04 Ben Elias , Nicholas Proudfoot , Max Wakefield