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Let $G$ be the circulant graph $C_n(S)$ with $S\subseteq\{ 1,\ldots,\left \lfloor\frac{n}{2}\right \rfloor\}$ and let $\Delta$ be its independence complex. We describe the well-covered circulant graphs with 2-dimensional $\Delta$ and…

Commutative Algebra · Mathematics 2018-07-17 Francesco Romeo , Giancarlo Rinaldo

This study is the first part of a detailed study on Type-2 isomorphic circulant graphs having ten parts \cite{v2-1}-\cite{v2-10}. Circulant graphs $C_n(R)$ and $C_n(S)$ are said to be \emph{Adam's isomorphic} if there exist some $a\in…

Combinatorics · Mathematics 2026-05-13 Vilfred Kamalappan

The diameter of a graph is the maximum distance among all pairs of vertices. Thus a graph $G$ has diameter $d$ if any two vertices are at distance at most $d$ and there are two vertices at distance $d$. We are interested in studying the…

Combinatorics · Mathematics 2022-10-21 Laila Loudiki , Mustapha Kchikech , El Hassan Essaky

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

A circulant graph H is defined on the set of vertices V=\left\{ 1,\ldots,n\right\} and edges E=\left\{ \left(i,j\right):\left|i-j\right|\equiv s\left(\textrm{mod}n\right),s\in S\right\} , where S\subseteq\left\{…

Combinatorics · Mathematics 2017-07-17 Sebastian Richter , Israel Rocha

A $k$-dispersed labelling of a graph $G$ on $n$ vertices is a labelling of the vertices of $G$ by the integers $1, \dots , n$ such that $d(i,i+1) \geq k$ for $1 \leq i \leq n-1$. $DL(G)$ denotes the maximum value of $k$ such that $G$ has a…

Combinatorics · Mathematics 2023-10-17 William J. Martin , Douglas R. Stinson

In this paper, the dispersability of the Cartesian graph bundle over two cycles is completely solved. We show the Cartesian graph bundle $G$ over two cycles is dispersable if $G$ is bipartite; otherwise, $G$ is nearly dispersable.

Combinatorics · Mathematics 2024-05-28 Zeling Shao , Xiaoxiang Yu , Zhiguo Li

An $L(3,2,1)$-labeling of a graph $G$ is an assignment $f$ of nonnegative integers to vertices such that $\vert f(x)-f(y)\vert > 3-\mbox{dist}_G(x,y)$ for every pair $x,y$ of vertices of $G$, where $\mbox{dist}_G(x,y)$ denotes the distance…

Combinatorics · Mathematics 2026-05-13 Přemysl Holub , Martin Kopřiva

We describe a general approach of determining the distribution of spanning subgraphs in the random graph $\G(n,p)$. In particular, we determine the distribution of spanning subgraphs of certain given degree sequences, which is a…

Combinatorics · Mathematics 2015-01-16 Pu Gao

This study is the $2^{nd}$ part of a detailed study on Type-2 isomorphic circulant graphs having ten parts \cite{v2-1}-\cite{v2-10}. Definition of Type-2 isomorphism of circulant graphs $C_n(R)$ w.r.t. $m$ was further modified by the author…

Combinatorics · Mathematics 2026-05-13 Vilfred Kamalappan

A graph is called dispersable if it has a book embedding in which each page has maximum degree 1 and the number of pages is the maximum degree. Bernhart and Kainen conjectured every k-regular bipartite graph is dispersable. Forty years…

Combinatorics · Mathematics 2021-07-13 Paul C. Kainen , Shannon Overbay

We give necessary and sufficient conditions for a few classes of known circulant graphs and/or digraphs to be singular. The above graph classes are generalized to $(r,s,t)$-digraphs for non-negative integers $r,s$ and $t$, and the digraph…

Number Theory · Mathematics 2012-02-17 A. K. Lal , A. Satyanarayana Reddy

The book embedding of a graph $G$ is to place the vertices of $G$ on the spine and draw the edges to the pages so that the edges in the same page do not cross with each other. A book embedding is matching if the vertices in the same page…

Combinatorics · Mathematics 2021-07-05 Zeling Shao , Yanqing Liu , Zhiguo Li

In this paper we introduce the graph $\Gamma_{sc}(G)$ associated with a group $G$, called the solvable conjugacy class graph (abbreviated as SCC-graph), whose vertices are the nontrivial conjugacy classes of $G$ and two distinct conjugacy…

Combinatorics · Mathematics 2022-02-08 Parthajit Bhowal , Peter J. Cameron , Rajat Kanti Nath , Benjamin Sambale

This study is the $4^{th}$ part of a detailed study on Type-2 isomorphic circulant graphs having ten parts \cite{v2-1}-\cite{v2-10} and is a continuation of Part 3. Here, we study Type-2 isomorphic circulant graphs of order 54 and show that…

Combinatorics · Mathematics 2026-05-14 Vilfred Kamalappan

This short paper presents characterisations of normal arc-transitive circulants and arc-transitive normal circulants, that is, for a connected arc-transitive circulant $\Gamma=\Cay(C,S)$, it is shown that 1. Aut(C,S) is transitive on S if…

Combinatorics · Mathematics 2021-01-13 Shu Jiao Song

The jump graph $J(G)$ of a simple graph $G$ has vertices which represent edges in $G$ where two vertices in $J(G)$ are adjacent if and only if the corresponding edges in $G$ do not share an endpoint. In this paper, we examine sequences of…

Combinatorics · Mathematics 2022-05-05 Fran Herr , Legrand Jones

Given two sets $A$ and $B$ of integers, we consider the problem of finding a set $S \subseteq A$ of the smallest possible cardinality such the greatest common divisor of the elements of $S \cup B$ equals that of those of $A \cup B$. The…

Computational Complexity · Computer Science 2014-02-25 Joachim von zur Gathen , Igor E. Shparlinski

The matching book thickness of a graph is the least number of pages in a book embedding such that each page is a matching. A graph is dispersable if its matching book thickness equals its maximum degree. Minimum page matching book…

Combinatorics · Mathematics 2024-04-16 Paul C. Kainen , Samuel S. Joslin , Shannon Overbay

The diameter of a graph measures the maximal distance between any pair of vertices. The diameters of many small-world networks, as well as a variety of other random graph models, grow logarithmically in the number of nodes. In contrast, the…

Combinatorics · Mathematics 2011-04-05 Jens Marklof , Andreas Strömbergsson
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