Colombini, FerruccioDel Santo, DanieleFanelli, FrancescoMetivier, Guy2013-02-042013-02-042013-02-04https://openscience.sissa.it/handle/1963/6437In this paper we will study the Cauchy problem for strictly hyperbolic operators with low regularity coe fficients in any space dimension N ≥ 1. We will suppose the coe fficients to be log-Zygmund continuous in time and log-Lipschitz continuous in space. Paradifferential calculus with parameters will be the main tool to get energy estimates in Sobolev spaces and these estimates will present a time-dependent loss of derivatives.enPreprintMAT/05 ANALISI MATEMATICA