A characteristic polynomial of the Seidel matrix over $\mathbb{F}_3$

In this paper, we consider the condition when the characteristic polynomials of the Seidel matrix of the graphs are decomposed into products of linear polynomials over $\mathbb{F}_3$. We also show the equality over $\mathbb{F}_3$ between the characteristic polynomial of the Seidel matrix of a graph and the characteristic polynomial of the adjacency matrix of that graph.