Lรถwner-functions -- Generalized Lรถwner-functions -- A generalization of the class S(b) -- Functions with bounded boundary rotation -- Variation of Green's function -- The schiffer-condition for S(b)-functions -- The coefficient a3 -- The power inequality -- Application to the coefficient a3 and a4 -- Optimization of parameters for N=1 -- Optimization in the case N=3 -- The power inequality -- On generalizing the power inequality