Bifurcation of positive solutions for a semilinear equation with critical Sobolev exponent

In this note we consider bifurcation of positive solutions to the semilinear elliptic boundary-value problem with critical Sobolev exponent -∆u = λu - αu^p+ u^{2^*-1}, u ≥ 0, in Ω u=0, on Ω. where Ω is a bounded C^2-domain in R^n, n ≥ 3, λ > λ_1, 1 0 is a bifurcation parameter. Brezis and Nirenberg showed that a lower order (non-negative) perturbation can contribute to regain the compactness and whence yields existence of solutions. We study the equation with an indefinite perturbation and prove a bifurcation result of two solutions for this equation