Local bifurcation from the second eigenvalue of the Laplacian in a square

Abstract

In this work we study local bifurcation from the branch of trivial solutions for a class of semilinear elliptic equations, at the second eigenvalue λ 2 \lambda _2 of a square. We find that the bifurcation set can be locally described as the union of exactly four bifurcation branches of nontrivial solutions which cross the bifurcation point ( λ 2 , 0 ) (\lambda _2,0) . We also compute the Morse index of the solutions in the four branches.