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We define the class of high dimensional graph manifolds. These are compact smooth manifolds supporting a decomposition into finitely many pieces, each of which is diffeomorphic to the product of a torus with a finite volume hyperbolic…

Differential Geometry · Mathematics 2016-03-22 Roberto Frigerio , Jean-Francois Lafont , Alessandro Sisto

A connected graph is called \emph{geodetic} if there is a unique shortest path between each pair of vertices. We introduce a systematic method for constructing new presentations of free products that give rise to previously unknown geodetic…

Group Theory · Mathematics 2025-12-18 Joshua Abraham , Murray Elder , Adam Piggott , Kane Townsend

A twisting of a monoid $S$ is a map $\Phi:S\times S\to\mathbb{N}$ satisfying the identity $\Phi(a,b) + \Phi(ab,c) = \Phi(a,bc) + \Phi(b,c)$. Together with an additive commutative monoid $M$, and a fixed $q\in M$, this gives rise a so-called…

Group Theory · Mathematics 2025-10-24 James East , Robert D. Gray , P. A. Azeef Muhammed , Nik Ruškuc

Given two associative algebras A, C and a linear space V together with some linear maps R_1, R_2, R_3, E satisfying some conditions, we define an associative algebra structure on A\otimes V\otimes C called a two-sided crossed product.…

Quantum Algebra · Mathematics 2024-10-22 Florin Panaite

For a graph $G$, let $im(G)$ denote the maximum integer $t$ such that $G$ contains $K_t$ as an immersion. A recent paper of Collins, Heenehan, and McDonald (2023) studied the behaviour of this parameter under graph products, asking how…

Combinatorics · Mathematics 2025-11-24 Henry Echeverría , Andrea Jiménez , Suchismita Mishra , Daniel A. Quiroz , Mauricio Yépez

For a graph $G=(V,\ E)$ and a nonempty set $S\subseteq V$, the \emph{vertex boundary} of $S$, denoted by $\partial_G(S)$, is defined to be the set of vertices that are not in $S$ but have at least one neighbor in $S$. In this paper, for $G$…

Combinatorics · Mathematics 2025-10-07 Runze Wang

We establish for the first time the explicit curvature formulas for the horizontal and vertical edges of the strong product of two regular graphs. We complement this result with showing that there does not exist an analogous formula for the…

Combinatorics · Mathematics 2025-07-08 Guiqiang Mou

We provide a general framework on the coefficients of the graph polynomials of graphs which are Cartesian products. As a corollary, we prove that if $G=(V,E)$ is a graph with degrees of vertices $2d(v), v\in V$, and the graph polynomial…

Combinatorics · Mathematics 2022-01-19 Alexey Gordeev , Fedor Petrov

The tensor product of two graphs, $G$ and $H$, has a vertex set $V(G)\times V(H)$ and an edge between $(u,v)$ and $(u',v')$ iff both $u u' \in E(G)$ and $v v' \in E(H)$. Let $A(G)$ denote the limit of the independence ratios of tensor…

Combinatorics · Mathematics 2007-05-23 Noga Alon , Eyal Lubetzky

Given a graph $G$ and assuming that some vertices of $G$ are infected, the $r$-neighbor bootstrap percolation rule makes an uninfected vertex $v$ infected if $v$ has at least $r$ infected neighbors. The $r$-percolation number, $m(G,r)$, of…

Combinatorics · Mathematics 2024-09-13 Boštjan Brešar , Jaka Hedžet

We study the free product of rooted graphs and its various decompositions using quantum probabilistic methods. We show that the free product of rooted graphs is canonically associated with free independence, which completes the proof of the…

Combinatorics · Mathematics 2014-07-25 Luigi Accardi , Romuald Lenczewski , Rafal Salapata

We view hyper-graphs as incidence graphs, i.e. bipartite graphs with a set of nodes representing vertices and a set of nodes representing hyper-edges, with two nodes being adjacent if the corresponding vertex belongs to the corresponding…

Logic in Computer Science · Computer Science 2015-05-08 Nans Lefebvre

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

In this paper we study the hyperbolicity properties of a class of random groups arising as graph products associated to random graphs. Recall, that the construction of a graph product is a generalization of the constructions of right-angled…

Group Theory · Mathematics 2014-10-01 Ruth Charney , Michael Farber

In this paper we introduce a product-like operation that generalizes the construction of generalized Sierpi\'nski graphs. Let $G,H$ be graphs and let $f: V(G) \to V(H)$ be a function. Then the Sierpi\'nski product of $G$ and $H$ with…

Combinatorics · Mathematics 2019-04-09 Jurij Kovič , Tomaž Pisanski , Sara Sabrina Zemljič , Arjana Žitnik

A graph is \emph{well-dominated} if all of its minimal dominating sets have the same cardinality. We prove that at least one of the factors is well-dominated if the Cartesian product of two graphs is well-dominated. In addition, we show…

Combinatorics · Mathematics 2019-09-24 Sarah E. Anderson , Kirsti Kuenzel , Douglas F. Rall

We analyze the number of cliques of given size and the size of the largest clique in tensor product $G \times H$ of two Erd\H{o}s-R\'enyi graphs $G$ and $H$. Then an extended clustering coefficient is introduced and is studied for $G \times…

Combinatorics · Mathematics 2024-08-15 Umit Islak , Bugra Incekara

Let $G$ be a graph on $n$ vertices. An induced subgraph $H$ of $G$ is called heavy if there exist two nonadjacent vertices in $H$ with degree sum at least $n$ in $G$. We say that $G$ is $H$-heavy if every induced subgraph of $G$ isomorphic…

Combinatorics · Mathematics 2011-09-20 Binlong Li , Zdeněk Ryjáček , Ying Wang , Shenggui Zhang

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

For graphs $G$ and $H$, an $H$-coloring of $G$ is a function from the vertices of $G$ to the vertices of $H$ that preserves adjacency. $H$-colorings encode graph theory notions such as independent sets and proper colorings, and are a…

Combinatorics · Mathematics 2012-06-15 John Engbers , David Galvin