Improved overlap fermions

We test exact and approximate Ginsparg-Wilson fermions with respect to thei r chiral and scaling behavior in the 2-flavor Schwinger model. We first con sider explicit approximate GW fermions in a short range, then we proceed to their chiral correction by means of the "overlap formula", and finally we discuss a numerically efficient perturbative chiral correction. In this way we combine very good chiral and scaling properties with a relatively modes t computational effort.