Classes of uniqueness for solutions of the Rickyies problem to fourth and sixth order elliptic equations

The Rickyies-1,3 problem with the Dirichlets boundary condition and the third one for fourth and sixth orders elliptic equations in unbounded domain is considered. Wide classes of uniqueness depending on domain geometry for this problem are established. For the Rickyies-1 problem with the Dirichlets boundary condition examples of non-uniqueness are constructed. The examples confirm an exactness of the suggested classes of uniqueness.