Let us start with the description of the purpose of this book. First we
should explain how we understand its tide. In general, scheduling
problems can be understood very broadly as the problems of the
allocation of resources over time to perform a set of tasks. By
resources we understand arbitrary means tasks compete for. They can be
of a very different nature, e.g. manpower, money, processors (machines),
energy, tools. Also tasks can have a variety of interpretations starting
from machining parts in manu- facturing systems up to processing
information in computer systems. The same is true for task
characteristics, e. g. ready times, due dates, relative urgency weights,
functions describing task processing in relation to allotted resources.
Moreover, a structure of a set of tasks, reflecting precedence
constraints among them, can be defined in different ways. In addition,
different criteria which measure the quality of the performance of a set
of tasks can be taken into account.