let $r$ be a commutative ring. in this paper, by using algebraic properties of $r$, we study the hase digraph of prime ideals of $r$.

Transposition graph Tn is defined as a Cayley over the symmetric group generated by all transpositions. It known that eigenvalues of are integers. However, an explicit description spectrum unknown. In this paper we prove for any integer k⩾0 there exists n(k) such n⩾n(k) and m∈{0,…,k}, m eigenvalue Tn. particular, it proved zero n≠2, 1 odd n⩾7 even n⩾14. We also present exact values third fourth...

‎let $g$ be a graph without an isolated vertex‎, ‎the normalized laplacian matrix $tilde{mathcal{l}}(g)$‎‎is defined as $tilde{mathcal{l}}(g)=mathcal{d}^{-frac{1}{2}}mathcal{l}(g) mathcal{d}^{-frac{1}{2}}$‎, where ‎$‎mathcal{‎d}‎$ ‎is a‎ diagonal matrix whose entries are degree of ‎vertices ‎‎of ‎$‎g‎$‎‎. ‎the eigenvalues of‎‎$tilde{mathcal{l}}(g)$ are ‎called ‎ ‎ as ‎the ‎normalized laplacian ...

The prevalent communications networks suffer from lack of spectrum and spectrum inefficiency. This has motivated researchers to develop cognitive radio (CR) as a smart and dynamic radio access promised solution. A major challenge to this new technology is how to make fair assignment of available spectrum to unlicensed users, particularly for smart grids communication. This paper introduces an i...

Let G be a simple connected graph and {v_1,v_2,..., v_k} be the set of pendent (vertices of degree one) vertices of G. The reduced distance matrix of G is a square matrix whose (i,j)-entry is the topological distance between v_i and v_j of G. In this paper, we compute the spectrum of the reduced distance matrix of the generalized Bethe trees.

Let $R$ be a ring (not necessarily commutative) with nonzero identity. We define $Gamma(R)$ to be the graph with vertex set $R$ in which two distinct vertices $x$ and $y$ are adjacent if and only if there exist unit elements $u,v$ of $R$ such that $x+uyv$ is a unit of $R$. In this paper, basic properties of $Gamma(R)$ are studied. We investigate connectivity and the girth of $Gamma(R)$, where $...