Department of Mathematics, East China University of Science and Technology, Shanghai 200237, China
Copyright © 2012 Ruifang Zhao. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Let be the algebra generated in Sobolev space by the rational functions with poles outside the unit disk . In this paper, we study the similarity invariant of the multiplication operators in , when is univalent analytic on or is strongly irreducible. And the commutants of multiplication operators whose symbols are composite functions, univalent analytic functions, or entire functions are studied.