I had published papers on differential equations in Banach spaces; on interpolation, approximation, and embedding theorems for Sobolev and Besov functions on manifolds. In particular, I developed a theory of Sobolev, Besov and Paley-Wiener subspaces associated with representations of Lie groups in Banach and Hilbert spaces. I started analysis of traces of functions which are smooth with respect to nonholonomic vector fields (Hormander's condition). I initiated development of the so-called Shannon sampling and variational splines on compact and non-compact Riemannian and sub-Riemannian manifolds and applied them to Radon transform on manifolds; constructed Parseval localized frames (wavelets) on manifolds with applications to CMB. My development of Shannon sampling and splines on combinatorial and quantum graphs became one of the starting points of what is known as the Graph Signal Processing.