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In this short note we make a few remarks on a class of generalized incidence matrices whose matroids do not depend on the orientation of the underlying graph and natural commutative algebras associated to such matrices.

Combinatorics · Mathematics 2020-05-14 Boris Shapiro , Arkady Vaintrob

We show that the infinite matroid intersection conjecture of Nash-Williams implies the infinite Menger theorem proved recently by Aharoni and Berger. We prove that this conjecture is true whenever one matroid is nearly finitary and the…

Combinatorics · Mathematics 2012-07-10 Elad Aigner-Horev , Johannes Carmesin , Jan-Oliver Fröhlich

We study bases of the lattice generated by the cycles of an undirected graph, defined as the integer linear combinations of the 0/1-incidence vectors of cycles. We prove structural results for this lattice, including explicit formulas for…

Combinatorics · Mathematics 2020-10-26 Gennadiy Averkov , Anastasia Chavez , Jesus A. De Loera , Bryan R. Gillespie

This sequel to our paper (Infinite gammoids, 2014) considers minors and duals of infinite gammoids. We prove that a class of gammoids definable by digraphs not containing a certain type of substructure, called an outgoing comb, is…

Combinatorics · Mathematics 2014-11-11 Seyed Hadi Afzali Borujeni , Hiu Fai Law , Malte Müller

In this series we introduce and investigate the concept of connectoids, which captures the connectivity structure of various discrete objects like undirected graphs, directed graphs, bidirected graphs, hypergraphs or finitary matroids. In…

Combinatorics · Mathematics 2025-06-17 Nathan Bowler , Florian Reich

We define and study analogs of curve graphs for infinite type surfaces. Our definitions use the geometry of a fixed surface and vertices of our graphs are infinite multicurves which are bounded in both a geometric and a topological sense.…

Geometric Topology · Mathematics 2014-10-14 Ariadna Fossas , Hugo Parlier

We prove that the invariably generating graph of a finite group can have an arbitrarily large number of connected components with at least two vertices.

Group Theory · Mathematics 2021-02-15 Daniele Garzoni

Investigating a problem of B. Mohar, we show that every one-ended Hamiltonian cubic graph with end degree 3 contains a second Hamilton cycle. We also construct two examples showing that this result does not extend to give a third Hamilton…

Combinatorics · Mathematics 2017-05-22 Max Pitz

Given two graphs, a mapping between their edge-sets is cycle-continuous, if the preimage of every cycle is a cycle. The motivation for this notion is Jaeger's conjecture that for every bridgeless graph there is a cycle-continuous mapping to…

Combinatorics · Mathematics 2013-01-01 Robert Šámal

Komj\'ath, Milner, and Polat investigated when a finitary matroid admits a partition into circuits. They defined the class of ``finite matching extendable'' matroids and showed in their compactness theorem that those matroids always admit…

Combinatorics · Mathematics 2025-09-17 Nathan Bowler , Attila Joó

We generalize the well-studied notion of a modular pair of a finite matroid to arbitrary families of sets in infinite matroids, and use it to develop the theory of infinite matroids in several as-yet-unexplored areas. Our results include a…

Combinatorics · Mathematics 2026-04-23 Mattias Ehatamm , Peter Nelson , Fernanda Rivera Omana

Two of the natural topologies for infinite graphs with edge-ends are Etop and Itop. In this paper, we study and characterize them. We show that Itop can be constructed by inverse limits of inverse systems of graphs with finitely many…

General Topology · Mathematics 2016-12-20 Babak Miraftab

One generalization of ordinary matroids is symplectic matroids. While symplectic matroids were initially defined by their collections of bases, there has been no cryptomorphic definition of symplectic matroids in terms of circuits. We give…

Combinatorics · Mathematics 2020-09-22 Zhexiu Tu

We prove that for any weakly convergent sequence of finite graphs with bounded vertex degrees, there exists a topological limit graphing.

Combinatorics · Mathematics 2007-05-23 Gabor Elek

Every end of an infinite graph $ G $ defines a tangle of infinite order in $ G $. These tangles indicate a highly cohesive substructure in the graph if and only if they are closed in some natural topology. We characterize, for every finite…

Combinatorics · Mathematics 2025-05-16 Jay Lilian Kneip

A recent line of research has concentrated on exploring the links between analytic and combinatorial theories of submodularity, uncovering several key connections between them. In this context, Lov\'asz initiated the study of matroids from…

Combinatorics · Mathematics 2024-10-16 Kristóf Bérczi , Márton Borbényi , László Lovász , László Márton Tóth

The number of homomorphisms from a finite graph $F$ to the complete graph $K_n$ is the evaluation of the chromatic polynomial of $F$ at $n$. Suitably scaled, this is the Tutte polynomial evaluation $T(F;1-n,0)$ and an invariant of the cycle…

Combinatorics · Mathematics 2016-02-25 Andrew Goodall , Guus Regts , Lluis Vena

Separation systems are posets with additional structure that form an abstract setting in which tangle-like clusters in graphs, matroids and other combinatorial structures can be expressed and studied. This paper offers some basic theory…

Combinatorics · Mathematics 2025-05-16 Reinhard Diestel , Jay Lilian Kneip

We introduce a connectivity function for infinite matroids with properties similar to the connectivity function of a finite matroid, such as submodularity and invariance under duality. As an application we use it to extend Tutte's linking…

Combinatorics · Mathematics 2011-01-31 Henning Bruhn , Paul Wollan

In this note we introduce a notion of a morphism between two hyperbolic iterated function systems. We prove that the graph of a morphism is the attractor of an iterated function system, giving a Closed Graph Theorem, and show how it can be…

Dynamical Systems · Mathematics 2023-05-04 Alexander Mundey