ON THE EXISTENCE OF RADIAL SOLUTIONS OF A NONLINEAR ELLIPTIC BVP IN AN ANNULUS

In this paper we study the radial solutions of quasilinear elliptic BVP: (*) div(a(Absolute value of x, u, \delu\)delu) + f(Absolute value of x, u, \delu\) = 0, on A, u satisfies the Robin boundary conditions (2) below, where A = {x is-an-element-of R(n); a1 < Absolute value of x < a2}, a2 > a1 > 0, constants. Under the very general conditions, we prove that if f is superlinear at u = infinity, then (*) admits infinitely many radial solutions, and that each of them has a different (finite) number of zeros.