A Duduchava–Saginashvili's type theory for Wiener–Hopf plus Hankel operators

This paper presents a Duduchava–Saginashvili's type theory for Wiener–Hopf plus Hankel operators with semi-almost periodic Fourier symbols and acting between Lp Lebesgue spaces. This means the obtainment of one-sided invertibility and Fredholm property for these operators upon certain mean values of the representatives at infinity of their Fourier symbols. Additionally, a formula for the Fredholm index is provided by introducing a corresponding winding number of some new elements.