Super position of bubbles in a slightly supercritical Neumann problem

n this paper we consider the problem −Δu+u=up on a bounded domain with a homogeneous Neumann boundary condition. We prove the existence of a one-spike solution to (0.1) which concentrates around a topologically non trivial critical point of the mean curvature of the boundary with positive value. Under some symmetry assumption on Ω, namely if Ω is even with respect to N−1 variables and 0∈∂Ω is a point with positive mean curvature, we prove existence of solutions to (0.1) which resemble the form of a super-position of spikes centered at 0