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