Topics in Pseudo-DIfferential Operators

This Research Note presents in a clear and detailed manner a certain group of results pertaining to some variants, extensions and generalizations on the theory of pseudo-differential operators as introduced in the pioneering work of Kohn-Nirenberg. The author presents a discussion of concepts of order, true order and asymptotic expansions for general linear operators in some vector spaces, following a pattern appearing in pseudo-differential operator theory. The book is intended mainly for an audience of operator theorists, at a fairly elementary level; its main objective a unitary presentation of articles written by the author over a number of years.