“…The recent literature has shown that, in presence of homogeneus Neumann boundary conditions, quasilinear equations of the type (1.1) typically admit many positive solutions (in addition to the constant one) and that the set of positive solutions has a rich structure. We quote here the articles [31,32,13,1,2,3,41,40,29,39,9,7,8,33,18,6,20], some of which will be discussed later. Let us illustrate this fact in the semilinear case p = 2, when Ω is a ball and f (s) = s q−1 − s with q > 2.…”