Abstract: | Let be a bounded domain in , , with boundary , and consider the semilinear elliptic boundary value problem ![\begin{align*}L u &= \lambda a u + g(\cdot,u)u, \quad \text{in} \Omega , u &= 0, \quad \text{on} \partial \Omega , \end{align*}](http://www.ams.org/proc/2000-128-01/S0002-9939-99-05168-0/gif-abstract/img7.gif)
where is a uniformly elliptic operator on , , is strictly positive in , and the function is continuously differentiable, with , . A well known result of Rabinowitz shows that an unbounded continuum of positive solutions of this problem bifurcates from the principal eigenvalue of the linear problem. We show that under certain oscillation conditions on the nonlinearity , this continuum oscillates about , in a certain sense, as it approaches infinity. Hence, in particular, the equation has infinitely many positive solutions for each in an open interval containing . |