Summary: Online Algorithms:
A Study of Graph-Theoretic Concepts
Max-Planck-Institut fur Informatik, Im Stadtwald, 66123 Saarbrucken, Germany.
Abstract. In this paper we survey results on the design and analy-
sis of online algorithms, focusing on problems where graphs and graph-
theoretic concepts have proven particularly useful in the formulation or
in the solution of the problem. For each of the problems addressed, we
also present important open questions.
The traditional design and analysis of algorithms assumes that an algorithm,
which generates output, has complete knowledge of the entire input. However,
this assumption is often unrealistic in practical applications. Many of the algo-
rithmic problems that arise in practice are online. In these problems the input
is only partially available because some relevant input arrives only in the fu-
ture and is not accessible at present. An online algorithm must generate output
without knowledge of the entire input. Online problems arise in areas such as
resource allocation in operating systems, data structuring, robotics, distributed
computing and scheduling. We give some illustrative examples.