International Conference of Numerical Analysis and Applied Mathematics (ICNAAM), Kos, Greece, 19 - 25 September 2012, vol.1479, pp.954-956
We study the structure of generators of the Banach algebras (W-p((n)) [0,1],*) and (W-p((n)) [0,1], circle star), where * denotes the usual convolution and circle star the so-called Duhamel product. We also give a new characterization of a special class of composition operators acting in the Sobolev space W-p((n)) [0,1] by the formula (C-theta f) (x) = f (theta (x)).