Restrictions of unitary representations to subgroups and Ergodic theory: Group extensions and group cohomology.- Applications of group theory to quantum physics algebraic aspects.- Unitary representations of lie groups in quantum mechanics.- On certain unitary representations which arise from a quantization theory.- Derivation and solution of an infinite-component wave equation for the relativistic Coulomb problem.- Tensor operators for the group SL(2,C).- Lie algebras of local currents and their representations.- Infinite dimensional Lie algebras and current algebra.