Global Holder regularity for the fractional p-Laplacian

By virtue of barrier arguments we prove C-alpha-regularity up to the boundary for the weak solutions of a non-local, non-linear problem driven by the fractional p-Laplacian operator. The equation is boundedly inhomogeneous and the boundary conditions are of Dirichlet type. We employ different methods according to the singular (p < 2) of degenerate (p > 2) case.