Ferruccio ColombiniDipartimento di Matematica, Università di PisaHaruhisa IshidaInstitute of Mathematics, University of TsukubaNicola OrrúVia Genova 5, Sassari, Italy
This paper is devoted to the study of the Cauchy problem in$C$^{∞}and in the Gevrey classes for some second order degenerate hyperbolic equations with time dependent coefficients and lower order terms satisfying a suitable Levi condition.