Entropy quantities are connected with the 'degree of compactness' of
compact or precompact spaces, and so are appropriate tools for
investigating linear and compact operators between Banach spaces. The
main intention of this Tract is to study the relations between
compactness and other analytical properties, e.g. approximability and
eigenvalue sequences, of such operators. The authors present many
generalized results, some of which have not appeared in the literature
before. In the final chapter, the authors demonstrate that, to a certain
extent, the geometry of Banach spaces can also be developed on the basis
of operator theory. All mathematicians working in functional analysis
and operator theory will welcome this work as a reference or for
advanced graduate courses.