The importance of mathematics in the study of problems arising from the
real world, and the increasing success with which it has been used to
model situations ranging from the purely deterministic to the
stochastic, is well established. The purpose of the set of volumes to
which the present one belongs is to make available authoritative, up to
date, and self-contained accounts of some of the most important and
useful of these analytical approaches and techniques. Each volume
provides a detailed introduction to a specific subject area of current
importance that is summarized below, and then goes beyond this by
reviewing recent contributions, and so serving as a valuable reference
source. The progress in applicable mathematics has been brought about by
the extension and development of many important analytical approaches
and techniques, in areas both old and new, frequently aided by the use
of computers without which the solution of realistic problems would
otherwise have been impossible.