On a max-type and a min-type difference equation

This note shows that every positive solution to the following third order non–autonomous max-type difference equation

when is a three-periodic sequence of positive numbers, is periodic with period three. The same result was proved for the following min-type difference equation

     

Second-order energies on thin structures: variational theory and non-local effects

For a given positive measure μ on , we consider integral functionals of the kind

     

On the deficiency indices and self-adjointness of symmetric Hamiltonian systems

The main purpose of this paper is to investigate the formal deficiency indices of a symmetric first-order system