We derive the asymptotic spectral distribution of the distance k-graph of N-dimensional hypercube as N → ∞.

Let G be a finite connected graph on two or more vertices, and $G^{[N,k]}$ the distance-k graph of the N-fold Cartesian power of G. For a fixed k ≥ 1, we obtain explicitly the large N limit of the spectral distribution (the eigenvalue distribution of the adjacency matrix) of $G^{[N,k]}$. The limit distribution is described in terms of the Hermite polynomials. The proof is based on asymptotic combinatorics along with quantum probability theory.

Boolean matrices, the incidence matrices of a graph, are known not to be the (universal) matrices of a Boolean algebra. Here, we also show that their usual composition cannot make them the matrices of any algebra. Yet, later on, we "show" that it can. This seeming paradox comes from the hidden intrusion of a widespread set-theoretical (mis) definition and notation and denies its harmlessness. A minor modification of this standard definition might fix it.

If a graph is connected then the largest eigenvalue (i.e., index) generally changes (decreases or increases) if some local modifications are performed. In this paper two types of modifications are considered: (i) for a fixed vertex, t edges incident with it are deleted, while s new edges incident with it are inserted; (ii) for two non-adjacent vertices, t edges incident with one vertex are deleted, while s new edges incident with the other vertex are inserted. ...

Let $G$ be a simple connected graph of order $n$ with degree sequence $(d_1,d_2,...,d_n)$. Denote ${{(}^{\alpha }t)}_i={\sum }_{j:i\sim j}{d}_j^{\alpha }$, ${{(}^{\alpha }m)}_i={{(}^{\alpha }t)}_i/d_i^{\alpha }$ and ${{(}^{\alpha }N)}_i={\sum }_{j:i\sim j}{{(}^{\alpha }t)}_j$, where $\alpha$ is a real number. Denote by ${\lambda }_1\left(G\right)$ and ${\mu }_1\left(G\right)$ the spectral radius of the adjacency matrix and the Laplacian matrix of $G$, respectively. In this paper, we present some upper and lower bounds of ${\lambda }_1\left(G\right)$ and ${\mu }_1\left(G\right)$ in terms of ${{(}^{\alpha }t)}_i$, ${{(}^{\alpha }m)}_i$ and ${{(}^{\alpha }N)}_i$. Furthermore, we also characterize some extreme graphs which attain these upper bounds. These results theoretically improve and generalize some known results.

A total dominating set in a graph $G$ is a subset $X$ of $V\left(G\right)$ such that each vertex of $V\left(G\right)$ is adjacent to at least one vertex of $X$. The total domination number of $G$ is the minimum cardinality of a total dominating set. A function $f:V\left(G\right)\to \{-1,1\}$ is a signed dominating function (SDF) if the sum of its function values over any closed neighborhood is at least one. The weight of an SDF is the sum of its function values over all vertices. The signed domination number of $G$ is the minimum weight of an SDF on $G$. In this paper...

Let $A$ be an $n\times n$ symmetric, irreducible, and nonnegative matrix whose eigenvalues are ${\lambda }_1>{\lambda }_2\ge ...\ge {\lambda }_n$. In this paper we derive several lower and upper bounds, in particular on ${\lambda }_2$ and ${\lambda }_n$, but also, indirectly, on $\mu ={max}_{2\le i\le n}\left|{\lambda }_i\right|$. The bounds are in terms of the diagonal entries of the group generalized inverse, $Q^{\#}$, of the singular and irreducible M-matrix $Q={\lambda }_{1}I-A$. Our starting point is a spectral resolution for $Q^{\#}$. We consider the case of equality in some of these inequalities and we apply our results to the algebraic connectivity of undirected...

The energy of a molecular graph G is defined as the summation of the absolute values of the eigenvalues of adjacency matrix of a graph G. In this paper, an infinite class of fullerene graphs with 10n vertices, n ≥ 2, is considered. By proving centrosymmetricity of the adjacency matrix of these fullerene graphs, a lower bound for its energy is given. Our method is general and can be extended to other class of fullerene graphs.

The Mₙ-matrix was defined by Mohan [21] who has shown a method of constructing (1,-1)-matrices and studied some of their properties. The (1,-1)-matrices were constructed and studied by Cohn [6], Ehrlich [9], Ehrlich and Zeller [10], and Wang [34]. But in this paper, while giving some resemblances of this matrix with a Hadamard matrix, and by naming it as an M-matrix, we show how to construct partially balanced incomplete block designs and some regular graphs by it. Two types of these M-matrices...