Smoothness of bifurcation branches for a Signorini problem was proved. Location of bifurcation points for reaction-diffusion systems with various unilateral conditions was described. The result is surprising in the case of Signorini-Neumann conditions.
Smoothness, direction and stability of bifurcating branches for variational inequalities on nonconvex sets, global bifurcation for reaction-diffusion systems with nonstandard conditions and smooth dependence on data for the Signorini problem were given.
A smooth dependence of solutions and contact sets on parameters and existence of smooth bifurcation branches for certain classes of variational inequalities was proved. In particular cases, even direction, stability and global behaviour of bifurcation branches were described.