Differential Operators on Manifolds Lectures: M.F. Atiyah: Classical groups and classical differential operators on manifolds. R. Bott: Some aspects of invariant theory in differential geometry. E.M. Stein: Singular integral operators and nilpotent groups. Seminars: P. Malliavin: Diffusion et géométrie différentielle globale. S. Helgason: Solvability of invariant differential operators on homonogeneous manifolds. Lectures: M.F. Atiyah: Classical groups and classical differential operators on manifolds R. Bott: Some aspects of invariant theory in differential geometry E.M. Stein: Singular integral operators and nilpotent groups Seminars: P. Malliavin: Diffusion et géométrie différentielle globale S. Helgason: Solvability of invariant differential operators on homonogeneous manifolds.