LIFE SPAN OF NONNEGATIVE SOLUTIONS TO CERTAIN QUASILINEAR PARABOLIC CAUCHY PROBLEMS

We consider the problem (x)ut u m = h(x,t)u 1+p , x 2 R N , t > 0, with nonnegative, nontrivial, continuous initial condition, u(x,0) = u0(x) 6 0, u0(x) 0, x 2 R N. An integral inequality is obtained that can be used to find an exponent pc such that this problem has no nontrivial global solution when p pc. This integral inequality may also be used to estimate the maximal T > 0 such that there is a solution for 0 t 0, by obtaining a bound of the form T C0 #.