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In combinatorial commutative algebra and algebraic statistics many toric ideals are constructed from graphs. Keeping the categorical structure of graphs in mind we give previous results a more functorial context and generalize them by…

Commutative Algebra · Mathematics 2011-10-04 Alexander Engstrom , Patrik Noren

The discrete polymatroids and their base rings are studied recently in many papers (see \cite{HH}, \cite{HHV}, \cite{V1}, \cite{V2}). It is important to give conditions when the base ring associated to a transversal polymatroid is…

Commutative Algebra · Mathematics 2008-05-20 Alin Ştefan

In this paper, the principal tool to describe transversal polymatroids with Gorenstein base ring is polyhedral geometry, especially the $Danilov-Stanley$ theorem for the characterization of canonical module. Also, we compute the…

Commutative Algebra · Mathematics 2008-01-16 Alin Stefan

Bicircular lift matroids are a class of matroids defined on the edge set of a graph. For a given graph $G$, the circuits of its bicircular lift matroid are the edge sets of those subgraphs of $G$ that contain at least two cycles, and are…

Combinatorics · Mathematics 2016-07-05 Rong Chen , Zifei Gao

The vertices of a $k$-token graph of a graph $G$ correspond to $k$ indistinguishable tokens placed on $k$ different vertices of $G$. Changing some conditions on both the nature of the tokens and the number of tokens allowed in each vertex…

Combinatorics · Mathematics 2026-04-07 Xiaodi Song , Cristina Dalfó , Miquel Àngel Fiol , Mercè Mora , Shenggui Zhang

Matroids are ubiquitous in modern combinatorics. As discovered by Gelfand, Goresky, MacPherson and Serganova there is a beautiful connection between matroid theory and the geometry of Grassmannians: realizable matroids correspond to torus…

Combinatorics · Mathematics 2018-11-02 Amanda Cameron , Rodica Dinu , Mateusz Michałek , Tim Seynnaeve

This paper introduces Dirichlet matroids, a generalization of graphic matroids arising from electrical networks. We present four main theorems. First, we exhibit a matroid quotient involving geometric duals of networks embedded in surfaces…

Combinatorics · Mathematics 2022-06-02 Bob Lutz

This is an introductory paper about the category of regular oriented matroids (ROMs). We compare the homotopy types of the categories of regular and binary matroids. For example, in the unoriented case, they have the same fundamental group…

Combinatorics · Mathematics 2009-11-17 Kiyoshi Igusa

Halin proved that every minimally $k$-connected graph has a vertex of degree $k$. More generally, does every minimally vertically $k$-connected matroid have a $k$-element cocircuit? Results of Murty and Wong give an affirmative answer when…

Combinatorics · Mathematics 2022-05-27 James Oxley , Zach Walsh

In 30's Hassler Whitney considered and completely solved the problem $(WP)$ of describing the classes of graphs $G$ having the same cycle matroid $M(G)$. A natural analog $(WP)'$ of Whitney's problem $(WP)$ is to describe the classes of…

Combinatorics · Mathematics 2015-09-01 José F. De Jesús , Alexander Kelmans

We investigate Gauss maps of (not necessarily normal) projective toric varieties over an algebraically closed field of arbitrary characteristic. The main results are as follows: (1) The structure of the Gauss map of a toric variety is…

Algebraic Geometry · Mathematics 2014-03-05 Katsuhisa Furukawa , Atsushi Ito

Frame matroids and lifted-graphic matroids are two distinct minor-closed classes of matroids, each of which generalises the class of graphic matroids. The class of quasi-graphic matroids, recently introduced by Geelen, Gerards, and Whittle,…

Combinatorics · Mathematics 2017-06-21 Daryl Funk , Dillon Mayhew

Let $G$ be a finite undirected multigraph with no self-loops. The Jacobian $\operatorname{Jac}(G)$ is a finite abelian group associated with $G$ whose cardinality is equal to the number of spanning trees of $G$. There are only a finite…

Combinatorics · Mathematics 2021-01-19 Hahn Lheem , Deyuan Li , Carl Joshua Quines , Jessica Zhang

We specify what is meant for a polytope to be reconstructible from its graph or dual graph. And we introduce the problem of class reconstructibility, i.e., the face lattice of the polytope can be determined from the (dual) graph within a…

Combinatorics · Mathematics 2022-08-05 Guillermo Pineda-Villavicencio , Benjamin Schröter

Let $I_G$ be the binomial edge ideal on the generic 2 x n - Hankel matrix associated with a closed graph $G$ on the vertex set [n]. We characterize the graphs $G$ for which $I_G$ has maximal regularity and is Gorenstein.

Commutative Algebra · Mathematics 2015-12-02 Ahmet Dokuyucu , Ajdin Halilovic , Rida Irfan

There has been wide interest in understanding which properties of base graphs of matroids extend to base-cobase graphs of matroids. A significant result of Naddef and Pulleyblank (1984) shows that the $1$-skeleton of any $(0,1)$-polytope is…

Combinatorics · Mathematics 2025-06-30 Leonardo Martínez-Sandoval , Kolja Knauer

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 this paper, we study toric ideals associated with multichains of posets. It is shown that the comparability graph of a poset is chordal if and only if there exists a quadratic Gr\"obner basis of the toric ideal of the poset. Strong…

Combinatorics · Mathematics 2018-09-03 Hidefumi Ohsugi , Takayuki Hibi

We study lattice path matroid polytopes using their alcoved triangulation. We characterize Gorenstein lattice path matroid polytopes, yielding a new class of matroids satisfying the unimodality conjecture of de Loera, Haws, and K{\"o}ppe.…

Combinatorics · Mathematics 2023-03-21 Carolina Benedetti , Kolja Knauer , Jerónimo Valencia-Porras

We classify path polyominoes which are level and pseudo-Gorenstein. Moreover, we compute all level and pseudo-Gorenstein simple thin polyominoes with rank less than or equal to 10. We also compute the regularity of the pseudo-Gorenstein…

Commutative Algebra · Mathematics 2023-09-12 Giancarlo Rinaldo , Francesco Romeo , Rajib Sarkar
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