Díaz Díaz, Jesús IldefonsoRamos Del Olmo, Ángel Manuel2023-06-202023-06-201997-060764-444210.1016/S0764-4442(99)80407-8https://hdl.handle.net/20.500.14352/57404We study the approximate controllability property for y(t) - Delta phi(y) = u chi(omega), on Omega x (0, T), where Omega is a bounded open set of R-N and omega subset of Omega. First, we show some negative results for the case phi(s) = \s\(m-1)s, 0 < m < 1, by means of an obstruction phenomenon. In a second part, we obtain a positive answer on the space H-1-gamma(Omega), for any gamma > 0, for a class of functions phi essentially linear at infinity, by using a higher order vanishing viscosity argument.frajournal articlehttp://www.sciencedirect.com/science/article/pii/S0764444299804078http://www.sciencedirect.com/restricted access517.977quasilinear diffusion equationapproximate controllabilityEcuaciones diferenciales1202.07 Ecuaciones en Diferencias