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Related papers: Graph products of right cancellative monoids

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We generalize a previous result of Stevenson to the category of dendroidal sets, yielding the right cancellation property of dendroidal inner anodynes within the class of normal monomorphisms. As an application of this property, we show how…

Category Theory · Mathematics 2024-07-30 Miguel Barata

Let $G$ be an undirected graph on $n$ vertices and let $S(G)$ be the set of all $n \times n$ real symmetric matrices whose nonzero off-diagonal entries occur in exactly the positions corresponding to the edges of $G$. The inverse eigenvalue…

Spectral Theory · Mathematics 2014-01-10 Polona Oblak , Helena Šmigoc

Let ${\mathcal D}_{n,d}$ be the set of all $d$-regular directed graphs on $n$ vertices. Let $G$ be a graph chosen uniformly at random from ${\mathcal D}_{n,d}$ and $M$ be its adjacency matrix. We show that $M$ is invertible with probability…

We show that every irreducible toroidal integer homology sphere graph manifold has a left-orderable fundamental group. This is established by way of a specialization of a result due to Bludov and Glass for the almagamated products that…

Geometric Topology · Mathematics 2014-10-01 Adam Clay , Tye Lidman , Liam Watson

A monoid is said to be special if it admits a presentation in which all defining relations are of the form $w = 1$. Groups are familiar examples of special monoids. This article studies the geometric and structural properties of the Cayley…

Group Theory · Mathematics 2021-01-20 Carl-Fredrik Nyberg-Brodda

We give a new definition of the semigroup C*-algebra of a left cancellative semigroup, which resolves problems of the construction by X. Li. Namely, the new construction is functorial, and the independence of ideals in the semigroup does…

Operator Algebras · Mathematics 2019-05-07 Marat Aukhadiev

A set S of vertices of a connected graph G is convex, if for any pair of vertices u; v 2 S, every shortest path joining u and v is contained in S . The convex hull CH(S) of a set of vertices S is defined as the smallest convex set in G…

Combinatorics · Mathematics 2010-06-08 Jose Caceres , Carmen Hernando , Merce Mora , Ignacio M. Pelayo , Maria Luz Puertas

Conduction graphs are defined here in order to elucidate at a glance the often complicated conduction behaviour of molecular graphs as ballistic molecular conductors. The graph $G^{\mathrm C}$ describes all possible conducting devices…

Combinatorics · Mathematics 2024-09-23 Aidan Birkinshaw , Patrick W. Fowler , Jan Goedgebeur , Jorik Jooken

Let $G$ be a simple graph with $m$ edges and $H_i$, $1\leq i \leq m$ be simple graphs too. The generalized edge corona product of graphs $G$ and $H_1, ..., H_m$, denoted by $G \diamond (H_1, ..., H_m)$, is obtained by taking one copy of…

Combinatorics · Mathematics 2017-12-14 Irandokht Rezaee Abdolhosseinzadeh , Freydoon Rahbarnia

Let (P,<) be a finite poset and let G be its comparability graph. If cl(G) is the clutter of maximal cliques of G, we prove that cl(G) satisfies the max-flow min-cut property and that its edge ideal is normally torsion free. We prove that…

Commutative Algebra · Mathematics 2011-04-05 Luis A. Dupont , Rafael H Villarreal

Let $G$ be a simple graph and $I(G)$ be its edge ideal. In this article, we study the Castelnuovo-Mumford regularity of symbolic powers of edge ideals of join of graphs. As a consequence, we prove Minh's conjecture for wheel graphs,…

Commutative Algebra · Mathematics 2020-08-04 Arvind Kumar , Rajiv Kumar , Rajib Sarkar

A graph is said to be well-edge-dominated if all its minimal edge dominating sets are minimum. It is known that every well-edge-dominated graph $G$ is also equimatchable, meaning that every maximal matching in $G$ is maximum. In this paper,…

Combinatorics · Mathematics 2021-10-15 Sarah E. Anderson , Kirsti Kuenzel , Douglas F. Rall

We study two classes of inverse semigroups built from directed graphs, namely graph inverse semigroups and a new class of semigroups that we refer to as Leavitt inverse semigroups. These semigroups are closely related to graph…

Group Theory · Mathematics 2019-11-19 John Meakin , Zhengpan Wang

The left-ideal relation graph on a ring $R$, denoted by $\overrightarrow{\Gamma_{l-i}}(R)$, is a directed graph whose vertex set is all the elements of $R$ and there is a directed edge from $x$ to a distinct $y$ if and only if the left…

Combinatorics · Mathematics 2022-01-10 Jitender Kumar , Barkha Baloda , Sanjeet Malhotra

A categorical formalism for directed graphs is introduced, featuring natural notions of morphisms and subgraphs, and leading to two elementary descriptions of the free-properad monad, first in terms of presheaves on elementary graphs,…

Quantum Algebra · Mathematics 2016-10-04 Joachim Kock

Our purpose is to study the family of simple undirected graphs whose toric ideal is a complete intersection from both an algorithmic and a combinatorial point of view. We obtain a polynomial time algorithm that, given a graph $G$, checks…

Commutative Algebra · Mathematics 2015-07-14 Isabel Bermejo , Ignacio García-Marco , Enrique Reyes

This article investigates the isomorphism problem for graphs derived from the four standard graph products: Cartesian, Kronecker (direct), strong, and lexicographic product. We provide a complete characterization of all simple connected…

Combinatorics · Mathematics 2025-08-07 Priti Prasanna Mondal , M. Rajesh Kannan , Fouzul Atik

The first author showed in a previous paper that there is a correspondence between self-similar group actions and a class of left cancellative monoids called left Rees monoids. These monoids can be constructed either directly from the…

Category Theory · Mathematics 2014-11-11 Mark V. Lawson , Alistair R. Wallis

In this paper, we study rooted products of graphs from the perspective of combinatorial commutative algebra. For edge ideals, we introduce the 2-Cohen-Macaulayness with respect to a vertex and use it to investigate when edge ideals of…

Commutative Algebra · Mathematics 2025-12-09 Yuji Muta , Naoki Terai

A graph is well-(edge-)dominated if every minimal (edge) dominating set is minimum. A graph is equimatchable if every maximal matching is maximum. We study these concepts on strong product graphs. We fully characterize well-edge-dominated…

Combinatorics · Mathematics 2024-07-02 Yixin Cao , Guiqiang Mou , Jianxin Wang