La méthode de Kikuchi appliquée aux équations de von Karman.
Le equazioni funzionali in analisi non lineare
Lie-point symmetries in bifurcation problems
Local properties of the solution set of the operator equation in Banach spaces in a neighbourhood of a bifurcation point
In this work we study the problem of the existence of bifurcation in the solution set of the equation F(x, λ)=0, where F: X×R k →Y is a C 2-smooth operator, X and Y are Banach spaces such that X⊂Y. Moreover, there is given a scalar product 〈·,·〉: Y×Y→R 1 that is continuous with respect to the norms in X and Y. We show that under some conditions there is bifurcation at a point (0, λ0)∈X×R k and we describe the solution set of the studied equation in a small neighbourhood of this point.
Lyapunov center theorem for some nonlinear PDE's : a simple proof