Multi-bubble nodal solutions for slightly subcritical elliptic problems in domains with symmetries

We study the existence of sign-changing solutions with multiple bubbles to the slightly subcritical problem−Δu=|u|2⁎−2−εuin Ω,u=0on ∂Ω, where Ω is a smooth bounded domain in RN, N⩾3, 2⁎=2NN−2 and ε>0 is a small parameter. In particular we prove that if Ω is convex and satisfies a certain symmetry, then a nodal four-bubble solution exists with two positive and two negative bubbles.