Conservation of the mass for solutions to a class of singular parabolic equations

In this paper we deal with the Cauchy problem associated to a class of quasilinear singular parabolic equations with L^∞ cofficients, whose prototypes are the p-Laplacian (Formula presented.) and the Porous medium equation (Formula presented.). In this range of the parameters p and m, we are in the so called fast di¤usion case. We prove that the initial mass is preserved for all the times.