On optimal parameters involved with two-weighted estimates of commutators of singular and fractional operators with Lipschitz symbols

summary:We prove two-weighted norm estimates for higher order commutator of singular integral and fractional type operators between weighted Lᵖ and certain spaces that include Lipschitz, BMO and Morrey spaces. We also give the optimal parameters involved with these results, where the optimality is understood in the sense that the parameters defining the corresponding spaces belong to a certain region out of which the classes of weights are satisfied by trivial weights. We also exhibit pairs of nontrivial weights in the optimal region satisfying the conditions required.