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We introduce a new notation for representing labeled regular bipartite graphs of arbitrary degree. Several enumeration problems for labeled and unlabeled regular bipartite graphs have been introduced. A general algorithm for enumerating all…

Discrete Mathematics · Computer Science 2015-12-31 Vivek S. Nittoor

In light of Lov\'{a}sz's longstanding question on the existence of Hamilton paths in vertex-transitive graphs, this paper considers a natural variant: what if vertex-transitivity is relaxed, yet a high degree of symmetry--specifically…

Combinatorics · Mathematics 2026-02-17 Shaofei Du , Kai Yuan

For families of 4-regular directed circulant graphs with $n$ vertices, we count the number of primitive periodic orbits of length up to at least $n$. The relevant counting techniques are then extended to count the number of primitive pseudo…

Combinatorics · Mathematics 2021-09-29 Lauren Engelthaler , Isaac Hellerman , Tori Hudgins

A CIS graph is a graph in which every maximal stable set and every maximal clique intersect. A graph is well-covered if all its maximal stable sets are of the same size, co-well-covered if its complement is well-covered, and…

Combinatorics · Mathematics 2016-08-08 Edward Dobson , Ademir Hujdurović , Martin Milanič , Gabriel Verret

The chordal ring (CR) graphs are a well-known family of graphs used to model some interconnection networks for computer systems in which all nodes are in a cycle. Generalizing the CR graphs, in this paper, we introduce the families of…

Combinatorics · Mathematics 2024-09-04 M. A. Reyes , C. Dalfó , M. A. Fiol

We consider the following problem closely related to graph isomorphism. In a simplified version, the task is to compute the automorphism group of a given set family (or a hypergraph), that is, the group of all automorphisms of the given…

Discrete Mathematics · Computer Science 2022-06-29 Deniz Ağaoğlu Çağırıcı , Petr Hliněný

The spectrum of the normalized Laplacian matrix cannot determine the number of edges in a graph, however finding constructions of cospectral graphs with differing number of edges has been elusive. In this paper we use basic properties of…

Combinatorics · Mathematics 2014-10-27 Steve Butler

Starting from context-free inverse graphs, we introduce a new class of groups and study their structural properties. We establish closure properties, show that their co-word problems are context-free, analyze torsion elements, and realize…

Group Theory · Mathematics 2025-11-18 Daniele D'Angeli , Francesco Matucci , Davide Perego , Emanuele Rodaro

In this article we study the automorphism groups of binary cyclic codes. In particular, we provide explicit constructions for codes whose automorphism groups can be described as (a) direct products of two symmetric groups or (b) iterated…

Combinatorics · Mathematics 2009-03-23 Rolf Bienert , Benjamin Klopsch

We study the automorphism group of graphons (graph limits). We prove that after an appropriate "standardization" of the graphon, the automorphism group is compact. Furthermore, we characterize the orbits of the automorphism group on…

Combinatorics · Mathematics 2021-02-17 László Lovász , Balázs Szegedy

Extending earlier results of Godsil and of Dobson and Malnic on Johnson graphs, we characterise those merged Johnson graphs $J=J(n,k)_I$ which are Cayley graphs, that is, which are connected and have a group of automorphisms acting…

Combinatorics · Mathematics 2015-09-11 Gareth A. Jones , Robert Jajcay

Metacirculants are a rich resource of many families of interesting graphs, and weak metacirculants are generalizations of them. A graph is called a {\em split weak metacirculant} if it has a vertex-transitive split metacyclic automorphism…

Combinatorics · Mathematics 2018-10-04 Li Cui , Jin-Xin Zhou

A nut graph is a simple graph whose adjacency matrix has the eigenvalue~0 with multiplicity~1 such that its corresponding eigenvector has no zero entries. Motivated by a question of Fowler et al.~[\emph{Disc. Math. Graph Theory} 40 (2020),…

Combinatorics · Mathematics 2021-06-03 Ivan Damnjanović , Dragan Stevanović

A graph $\Ga$ is $G$-symmetric if $\Ga$ admits $G$ as a group of automorphisms acting transitively on the set of vertices and the set of arcs of $\Ga$, where an arc is an ordered pair of adjacent vertices. In the case when $G$ is…

Combinatorics · Mathematics 2013-11-27 Guangjun Xu , Sanming Zhou

In this study, we obtain the following two families of circulant graphs each has Type-2 isomorphic circulant graphs w.r.t. $m$ such that $m$ has more than one value. (i) Family of circulant graphs $C_{432}(R)$, each has isomorphic circulant…

Combinatorics · Mathematics 2026-05-15 Vilfred Kamalappan

We explore algebraic and spectral properties of weighted graphs containing twin vertices that are useful in quantum state transfer. We extend the notion of adjacency strong cospectrality to arbitrary Hermitian matrices, with focus on the…

Combinatorics · Mathematics 2023-12-29 Hermie Monterde

A circulant is a Cayley graph over a cyclic group. A well-covered graph is a graph in which all maximal stable sets are of the same size, or in other words, they are all maximum. A CIS graph is a graph in which every maximal stable set and…

Combinatorics · Mathematics 2014-02-11 Endre Boros , Vladimir Gurvich , Martin Milanic

A finite graph is called a tricirculant if admits a cyclic group of automorphism which has precisely three orbits on the vertex-set of the graph, all of equal size. We classify all finite connected cubic vertex-transitive tricirculants. We…

Combinatorics · Mathematics 2018-12-12 Primož Potočnik , Micael Toledo

This article initiates a geometric study of the automorphism groups of general graph products of groups, and investigates the algebraic and geometric structure of automorphism groups of cyclic product of groups. For a cyclic product of at…

Group Theory · Mathematics 2018-03-21 Anthony Genevois , Alexandre Martin

Let $G$ be a $p$-group. We begin to consider the relationship between the structure of the commuting graph and $|G:Z(G)|$. We also build a family of groups whose commuting graphs have more than one connected component whose diameter is at…

Group Theory · Mathematics 2025-11-18 Mark L. Lewis , Ryan McCulloch
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