Leonardo de Lima

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math.SP2014

A lower bound for the sum of the two largest signless Laplacian eigenvalues

Leonardo de Lima, Carla Oliveira

Let $G$ be a graph of order $n \geq 3$ with sequence degree given as $d_{1} (G) \geq ... \geq d_{n} (G)$ and let $μ_{1} (G), ..., μ_{n} (G)$ and $q_{1} (G), ..., q_{n} (G)$ be the Laplacian and…

math.SP2014

Spectra of the blow-up graphs

Carla Oliveira, Leonardo de Lima, Vladimir Nikiforov

Let $G$ be graph on $n$ vertices and $G^{(t)}$ its blow-up graph of order $t .$ In this paper, we determine all eigenvalues of the Laplacian and the signless Laplacian matrix of $G^…