On formal products and the Seidel spectrum of graphs

Mirko Lepovi\'c

Abstract: In Lepovi\'c [2] using the formal product and the so-called formal generating functions, we proved some results concerning cospectral graphs. In this paper, we define the Seidel formal product and investigate some properties of the Seidel spectrum. In particular, for any two overgraphs $G_{S_1}$ and $G_{S_2}$ of $G$ we give necessary and sufficient conditions under which $G_{S_1}$ and $G_{S_2}$ have the same Seidel spectrum.

Classification (MSC2000): 05C50

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