For a simple connected graph $ G $ of order $ n $, the normalized Laplacian is a square matrix of order $ n $, defined as $\mathcal{ L}(G)= D(G)^{ -\frac{ 1}{ 2}}L(G)D(G)^{ -\frac{ 1}{ 2}}$, where $ D(G)^{ -\frac{ 1}{ 2}} $ is the diagonal matrix whose $ i$-th diagonal entry is $ \frac{ 1}{ \sqrt{ d_{ i}}} $. In this article, we find the normalized Laplacian eigenvalues of the joined union of regular graphs in terms of the adjacency eigenvalues and the eigenvalues of quotient matrix associated with graph $ G $. For a finite group $\mathcal{ G}$, the power graph $\mathcal{ P}(\mathcal{ G})$ of a group $ \mathcal{ G} $ is defined as the simple graph in which two distinct vertices are joined by an edge if and only if one is the power of other. As a consequence of the joined union of graphs, we investigate the normalized Laplacian eigenvalues of power graphs of finite cyclic group $ \mathbb{ Z}_{ n}. $
Categories: math.CO math.GR math.SP