Spectra and Randic spectra of caterpillar graphs and applications to the energy

Let $H$ be an undirected simple graph with vertices $v_{1},\ldots ,v_{k}$ and $G_{1},\ldots ,G_{k}$ be a sequence formed with $k$ disjoint graphs $G_{i}$, $i=1,\ldots ,k$. The $H$-generalized composition (or $H$% -join) of this sequence is denoted by $H\left[ G_{1},\ldots ,G_{k}\right] .$ In this work, we characterize the caterpillar graphs as a $H$-generalized composition and we study their spectra and Randi\'{c} spectra, respectively. As an application, we obtain an improved and tight upper bound for the Energy and the Randi\'{c} energy of these interesting trees

Albertson (Alb) spectral radii and Albertson (Alb) energies of graph operation

The sum of the absolute eigenvalues of the adjacency matrix make up graph energy. The greatest absolute eigenvalue of the adjacency matrix is represented by the spectral radius of the graph. Both molecular computing and computer science have uses for graph energies and spectral radii. The Albertson (Alb) energies and spectral radii of generalized splitting and shadow graphs constructed on any regular graph is the main focus of this study. The only thing that may be disputed is the comparison of the (Alb) energies and (Alb) spectral radii of the newly formed graphs to those of the base graph. By concentrating on splitting and shadow graph, we compute new correlations between the Alb energies and spectral radius of the new graph and the prior graph