These two volumes constitute texts for graduate courses in linear
operator theory. The reader is assumed to have a knowledge of both
complex analysis and the first elements of operator theory. The texts
are intended to concisely present a variety of classes of linear
operators, each with its own character, theory, techniques and tools.
For each of the classes, various differential and integral operators
motivate or illustrate the main results. Although each class is treated
seperately and the first impression may be that of many different
theories, interconnections appear frequently and unexpectedly. The
result is a beautiful, unified and powerful theory. The classes we have
chosen are representatives of the principal important classes of
operators, and we believe that these illustrate the richness of operator
theory, both in its theoretical developments and in its applicants.
Because we wanted the books to be of reasonable size, we were selective
in the classes we chose and restricted our attention to the main
features of the corresponding theories. However, these theories have
been updated and enhanced by new developments, many of which appear here
for the first time in an operator-theory text. In the selection of the
material the taste and interest of the authors played an important role.