After the book "Basic Operator Theory" by Gohberg-Goldberg was pub-
lished, we, that is the present authors, intended to continue with
another book which would show the readers the large variety of classes
of operators and the important role they play in applications. The book
was planned to be of modest size, but due to the profusion of results in
this area of analysis, the number of topics grew larger than ex- pected.
Consequently, we decided to divide the material into two volumes - the
first volume being presented now. During the past years, courses and
seminars were given at our respective in- stitutions based on parts of
the texts. These were well received by the audience and enabled us to
make appropriate choices for the topics and presentation for the two
vol- umes. We would like to thank G.J. Groenewald, A.B. Kuijper and
A.C.M. Ran of the Vrije Universiteit at Amsterdam, who provided us with
lists of remarks and corrections. We are now aware that the Basic
Operator Theory book should be revised so that it may suitably fit in
with our present volumes. This revision is planned to be the last step
of an induction and not the first.