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We define and study "semimatroids", a class of objects which abstracts the dependence properties of an affine hyperplane arrangement. We show that geometric semilattices are precisely the posets of flats of semimatroids. We define and…

Combinatorics · Mathematics 2007-05-23 Federico Ardila

It is well known that the class of transversal matroids is not closed under contraction or duality. In particular, after contracting a set of elements from a transversal matroid, the resulting matroid may or may not be transversal, and the…

Combinatorics · Mathematics 2024-09-24 Samuel Bastida

We show that the 4-variable generating function of certain orientation related parameters of an ordered oriented matroid is the evaluation at (x + u, y+v) of its Tutte polynomial. This evaluation contains as special cases the counting of…

Combinatorics · Mathematics 2012-05-25 Michel Las Vergnas

We provide a combinatorial study of split matroids, a class that was motivated by the study of matroid polytopes from a tropical geometry point of view. A nice feature of split matroids is that they generalize paving matroids, while being…

Combinatorics · Mathematics 2022-02-10 Kristóf Bérczi , Tamás Király , Tamás Schwarcz , Yutaro Yamaguchi , Yu Yokoi

We introduce and investigate multivariate Tutte polynomials, dichromatic polynomials, subset-corank polynomials, size-corank polynomials, and rank generating polynomials of semimatroids, which generalize the corresponding polynomial…

Combinatorics · Mathematics 2025-08-04 Houshan Fu

We use the geometry of the stellahedral toric variety to study matroids. We identify the valuative group of matroids with the cohomology ring of the stellahedral toric variety, and show that valuative, homological, and numerical equivalence…

Algebraic Geometry · Mathematics 2023-09-08 Christopher Eur , June Huh , Matt Larson

The intersection data of a hyperplane arrangement is described by a geometric lattice, or equivalently a simple matroid. There is a rich interplay between this combinatorial structure and the topology of the arrangement complement. In this…

Combinatorics · Mathematics 2025-04-22 Christin Bibby

The Tutte polynomial of a graph or a matroid, named after W. T. Tutte, has the important universal property that essentially any multiplicative graph or network invariant with a deletion and contraction reduction must be an evaluation of…

Combinatorics · Mathematics 2012-03-02 Criel Merino , Marcelino Ramírez-Ibáñez , Guadalupe Rodríguez Sanchez

For any minor-closed class of matroids over a fixed finite field, we state an exact structural characterization for the sufficiently connected matroids in the class. We also state a number of conjectures that might be approachable using the…

Combinatorics · Mathematics 2015-01-06 Jim Geelen , Bert Gerards , Geoff Whittle

We give a general multiplication-convolution identity for the multivariate and bivariate rank generating polynomial of a matroid. The bivariate rank generating polynomial is transformable to and from the Tutte polynomial by simple algebraic…

Combinatorics · Mathematics 2009-09-15 Joseph P. S. Kung

We introduce the active partition of the ground set of an oriented matroid perspective (or quotient, or strong map) on a linearly ordered ground set. The reorientations obtained by arbitrarily reorienting parts of the active partition share…

Combinatorics · Mathematics 2018-07-19 Emeric Gioan

A matroid is a combinatorial structure that captures and generalizes the algebraic concept of linear independence under a broader and more abstract framework. Matroids are closely related with many other topics in discrete mathematics, such…

Combinatorics · Mathematics 2022-03-16 Gianira N. Alfarano , Karan Khathuria , Simran Tinani

We give two graph theoretical characterizations of tope graphs of (complexes of) oriented matroids. The first is in terms of excluded partial cube minors, the second is that all antipodal subgraphs are gated. A direct consequence is a third…

Combinatorics · Mathematics 2019-05-29 Kolja Knauer , Tilen Marc

A class of matroids is introduced which is very large as it strictly contains all paving matroids as special cases. As their key feature these split matroids can be studied via techniques from polyhedral geometry. It turns out that the…

Combinatorics · Mathematics 2018-07-02 Michael Joswig , Benjamin Schröter

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

We study an operation in matroid theory that allows one to transition a given matroid into another with more bases via relaxing a \emph{stressed subset}. This framework provides a new combinatorial characterization of the class of split…

Combinatorics · Mathematics 2024-09-12 Luis Ferroni , Benjamin Schröter

We describe a natural geometric relationship between matroids and underlying flag matroids by relating the geometry of the greedy algorithm to monotone path polytopes. This perspective allows us to generalize the construction of underlying…

Combinatorics · Mathematics 2024-06-25 Alexander E. Black , Raman Sanyal

The theory of matroids has been generalized to oriented matroids and, recently, to arithmetic matroids. We want to give a definition of "oriented arithmetic matroid" and prove some properties like the "uniqueness of orientation".

Combinatorics · Mathematics 2020-07-20 Roberto Pagaria

We extend the notion of representation of a matroid to algebraic structures that we call skew partial fields. Our definition of such representations extends Tutte's definition, using chain groups. We show how such representations behave…

Combinatorics · Mathematics 2012-12-12 R. A. Pendavingh , S. H. M. van Zwam

The Tutte polynomial is a fundamental invariant associated to a graph, matroid, vector arrangement, or hyperplane arrangement. This short survey focuses on some of the most important results on Tutte polynomials of hyperplane arrangements.…

Combinatorics · Mathematics 2017-10-05 Federico Ardila