Green’s functions and spectral theory for the Hill’s equation

The aim of this paper is to show certain properties of the Green’s functions related to the Hill’s equation coupled with various two point boundary value conditions. We will obtain the expression of the Green’s function of Neumann, Dirichlet, Mixed and anti-periodic problems as a combination of the Green’s function related to periodic ones.As a consequence we will prove suitable results in spectral theory and deduce some comparison results for the solutions of the Hill’s equation with various boundary value conditions.