Quasilinear wave equations and dispersive effect

In this Note, our aim is the proof of local wellposedness for quasilinear w ave equations for initial delta less regular than what is required by energ y method. This implies to prove Strichartz type estimates for wave operator s whose coefficients are only lipschltz. We improve the index of regularity obtained in [1]. (C) Academie des Sciences/Elsevier, Paris.