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We provide a characterisation of when a single-element contraction of a transversal matroid is itself transversal. Using this characterisation, we define a new class of transversal matroids closed under minors, which we call path-circular…

Combinatorics · Mathematics 2025-11-18 Gerry Toft

Polymatroids can be considered as "fractional matroid" where the rank function is not required to be integer valued. Many, but not every notion in matroid terminology translates naturally to polymatroids. Defining cyclic flats of a…

Combinatorics · Mathematics 2019-10-15 Laszlo Csirmaz

Let $M$ be an arbitrary matroid with circuits $\mathcal{C}(M)$. We propose a definition of a derived matroid $\delta M$ that has as its ground set $\mathcal{C}(M)$. Unlike previous attempts of such a definition, our definition applies to…

Combinatorics · Mathematics 2022-12-22 Olga Kuznetsova , Ragnar Freij-Hollanti , Relinde Jurrius

We present exponential and super factorial lower bounds on the number of Hamiltonian cycles passing through any edge of the basis graphs of a graphic, generalized Catalan and uniform matroids. All lower bounds were obtained by a common…

We investigate an approach to matroid complexity that involves describing a matroid via a list of independent sets, bases, circuits, or some other family of subsets of the ground set. The computational complexity of algorithmic problems…

Combinatorics · Mathematics 2007-09-10 Dillon Mayhew

Cycle polytopes of matroids have been introduced in combinatorial optimization as a generalization of important classes of polyhedral objects like cut polytopes and Eulerian subgraph polytopes associated to graphs. Here we start an…

Combinatorics · Mathematics 2021-05-04 Tim Römer , Sara Saeedi Madani

We introduce delta-graphic matroids, which are matroids whose bases form graphic delta-matroids. The class of delta-graphic matroids contains graphic matroids as well as cographic matroids and is a proper subclass of the class of regular…

Combinatorics · Mathematics 2022-10-05 Duksang Lee , Sang-il Oum

It has recently been shown that infinite matroids can be axiomatized in a way that is very similar to finite matroids and permits duality. This was previously thought impossible, since finitary infinite matroids must have non-finitary…

Combinatorics · Mathematics 2012-07-12 Henning Bruhn , Reinhard Diestel

Frame matroids and lifted-graphic matroids are two interesting generalizations of graphic matroids. Here we introduce a new generalization, {\em quasi-graphic matroids}, that unifies these two existing classes. Unlike frame matroids and…

Combinatorics · Mathematics 2017-04-25 Jim Geelen , Bert Gerards , Geoff Whittle

The cycles of a graph give a natural cyclic ordering to their edge-sets, and these orderings are consistent in that two edges are adjacent in one cycle if and only if they are adjacent in every cycle in which they appear together. An…

Combinatorics · Mathematics 2023-04-11 Cameron Crenshaw , James Oxley

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

In this paper we employ Tutte's theory of bridges to derive a decomposition theorem for binary matroids arising from signed graphs. The proposed decomposition differs from previous decomposition results on matroids that have appeared in the…

Combinatorics · Mathematics 2015-03-17 Konstantinos Papalamprou , Leonidas Pitsoulis

An excluded minor characterization for the class of binary signed-graphic matroids with graphic cocircuits is provided. In this report we present the necessary computations for the case analysis in the proof.

Combinatorics · Mathematics 2012-05-07 Konstantinos Papalamprou , Leonidas Pitsoulis

This paper is a continuation of my paper "Lattices of flats for symplectic matroids". We explore geometric constructions originating from the lattice of flats of ranked symplectic matroids. We observe that a ranked symplectic matroid always…

Combinatorics · Mathematics 2026-01-08 Or Raz

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

In this paper we find a unique normal form for the symplectic matrix representation of the conjugacy class of a prime order element of the mapping-class group. We find a set of generators for the fundamental group of a surface with a…

Geometric Topology · Mathematics 2007-06-17 Jane Gilman

In this work we provide a decomposition theorem for the class of quaternary and non-binary signed-graphic matroids. This generalizes previous results for binary signed-graphic matroids and graphic matroids, and it provides the theoretical…

Combinatorics · Mathematics 2015-10-26 Leonidas Pitsoulis , Eleni-Maria Vretta

We introduce the minor-closed, dual-closed class of multi-path matroids. We give a polynomial-time algorithm for computing the Tutte polynomial of a multi-path matroid, we describe their basis activities, and we prove some basic structural…

Combinatorics · Mathematics 2024-08-07 Joseph E. Bonin , Omer Gimenez

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

Matroid theory is often thought of as a generalization of graph theory. In this paper we propose an analogous correspondence between embedded graphs and delta-matroids. We show that delta-matroids arise as the natural extension of graphic…

Combinatorics · Mathematics 2019-03-04 Carolyn Chun , Iain Moffatt , Steven D. Noble , Ralf Rueckriemen