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In 2004, Ehrenfeucht, Harju, and Rozenberg showed that any graph on a vertex set $V$ can be obtained from a complete graph on $V$ via a sequence of the operations of complementation, switching edges and non-edges at a vertex, and local…

Combinatorics · Mathematics 2020-04-20 James Oxley , Jagdeep Singh

We characterize a rich class of valuated matroids, called R-minor valuated matroids that includes the indicator functions of matroids, and is closed under operations such as taking minors, duality, and induction by network. We exhibit a…

Combinatorics · Mathematics 2024-11-27 Edin Husić , Georg Loho , Ben Smith , László A. Végh

In 1980, White conjectured that the toric ideal of a matroid is generated by quadratic binomials corresponding to a symmetric exchange. In this paper, we compute Gr\"obner bases of toric ideals associated with matroids and show that, for…

Commutative Algebra · Mathematics 2020-04-28 Ken-ichi Hayase , Takayuki Hibi , Koyo Katsuno , Kazuki Shibata

A new connection between two different necessary conditions for a polymatroid to be linearly representable is presented. Specifically, we prove that the existence of a tensor product with the uniform matroid of rank two on three elements…

Combinatorics · Mathematics 2025-02-20 Carles Padró

In this paper, we investigate the classes of matroid intersection admitting a solution for the problem of partitioning the ground set $E$ into $k$ common independent sets, where $E$ can be partitioned into $k$ independent sets in each of…

Combinatorics · Mathematics 2019-01-29 Kenjiro Takazawa , Yu Yokoi

We study valuated matroids, their tropical incidence relations, flag matroids and total positivity. This leads to a characterization of permutahedral subdivisions, namely subdivisions of regular permutahedra into generalized permutahedra.…

Combinatorics · Mathematics 2023-02-22 Michael Joswig , Georg Loho , Dante Luber , Jorge Alberto Olarte

As part of the recent developments in infinite matroid theory, there have been a number of conjectures about how standard theorems of finite matroid theory might extend to the infinite setting. These include base packing, base covering, and…

Combinatorics · Mathematics 2012-03-06 Nathan Bowler , Johannes Carmesin

Krieger's embedding theorem provides necessary and sufficient conditions for an arbitrary subshift to embed in a given topologically mixing $\mathbb{Z}$-subshift of finite type. For some $\mathbb{Z}^d$-subshifts of finite type, Lightwood…

Dynamical Systems · Mathematics 2025-05-07 Tom Meyerovitch

Every bi-uniform matroid is representable over all sufficiently large fields. But it is not known exactly over which finite fields they are representable, and the existence of efficient methods to find a representation for every given…

Combinatorics · Mathematics 2014-07-29 Simeon Ball , Carles Padró , Zsuzsa Weiner , Chaoping Xing

We introduce a notion of duality (due to Brylawski) that generalizes matroid duality to arbitrary rank functions. This generalized duality allows for generalized operations (deletion and contraction) and a generalized polynomial based on…

Combinatorics · Mathematics 2012-01-10 Gary Gordon

Coxeter matroids generalize matroids just as flag varieties of Lie groups generalize Grassmannians. Valuations of Coxeter matroids are functions that behave well with respect to subdivisions of a Coxeter matroid into smaller ones. We…

Combinatorics · Mathematics 2021-01-27 Christopher Eur , Mario Sanchez , Mariel Supina

Wei's celebrated Duality Theorem is generalized in several ways, expressed as duality theorems for linear codes over division rings and, more generally, duality theorems for matroids. These results are further generalized, resulting in two…

Information Theory · Computer Science 2009-10-13 Thomas Britz , Bård Heiseldel , Trygve Johnsen , Dillon Mayhew , Keisuke Shiromoto

For a matroid $M$ of rank $r$ on $n$ elements, let $b(M)$ denote the fraction of bases of $M$ among the subsets of the ground set with cardinality $r$. We show that $$\Omega(1/n)\leq 1-b(M)\leq O(\log(n)^3/n)\text{ as }n\rightarrow \infty$$…

Combinatorics · Mathematics 2016-10-24 Rudi Pendavingh , Jorn van der Pol

Let M to be a matroid defined on a finite set E. A subset L of E is locked in M if L is 2-connected in M, the complement of L is 2-connected in the dual M*, and min{r(L), r*(complement of L)} is greater than 1. In this paper, we prove that…

Combinatorics · Mathematics 2016-12-22 Brahim Chaourar

Matroid varieties are the closures in the Grassmannian of sets of points defined by specifying which Pl\"ucker coordinates vanish and which don't --- the set of nonvanishing Pl\"ucker coordinates forms a well-studied object called a…

Algebraic Geometry · Mathematics 2015-08-11 Nicolas Ford

Though the notion of exchangeability has been discussed in the causal inference literature under various guises, it has rarely taken its original meaning as a symmetry property of probability distributions. As this property is a standard…

Methodology · Statistics 2023-10-04 Olli Saarela , David A. Stephens , Erica E. M. Moodie

We consider multi-item exchange markets in which agents want to receive one of their target bundles of resources. The model encompasses well-studied markets for kidney exchange, lung exchange, and multi-organ exchange. We identify a general…

Computer Science and Game Theory · Computer Science 2020-07-10 Haris Aziz

In this work, we explore the application of modulus in matroid theory, specifically, the modulus of the family of bases of matroids. This study not only recovers various concepts in matroid theory, including the strength, fractional…

Combinatorics · Mathematics 2024-04-09 Huy Truong , Pietro Poggi-Corradini

A new isomorphism invariant of matroids is introduced, in the form of a quasisymmetric function. This invariant (1) defines a Hopf morphism from the Hopf algebra of matroids to the quasisymmetric functions, which is surjective if one uses…

Combinatorics · Mathematics 2020-06-01 Louis J. Billera , Ning Jia , Victor Reiner

This article is a survey of matroid theory aimed at algebraic geometers. Matroids are combinatorial abstractions of linear subspaces and hyperplane arrangements. Not all matroids come from linear subspaces; those that do are said to be…

Algebraic Geometry · Mathematics 2014-09-12 Eric Katz