  In this paper, we interpret the multiplicity of 1 in Laplacian spectra of
trees and prove that Faria's inequality turns to an equality in the case of
normal trees which yields that in any tree without a vertex of degree 2, Faria
equality holds and multiplicity of 1 in Laplacian spectrum will be equal to
star degree of the the tree. As a result we introduce a combinatorial procedure
for computing the multiplicity of 1. In the way to prove this results we will
introduce many transformation on graphs which are invariant regarding to the
multiplicity of 1. We also introduce an inequality for the multiplicity of 0 in
adjacency spectrum of graphs and again introduce a procedure to compute this
multiplicity in the case of trees.
