
It is a real pleasure, indeed an honor, for me to have been invited by
Mike Capobianco and John Molluzzo to write an introduction to this
imaginative and valuable addition to graph theory. Let me therefore present
a few of my thoughts on the current status of graph theory and how their
work contributes to the field.
Graphs have come a long way since 1736 when Leonhard Euler applied
a graphtheoretic argument to solve the problem of the seven Konigsberg
bridges. At first, interest in and results involving graphs came slowly. Two
centuries passed before the first book exclusively devoted to graphs was
written. Its author, Denes Konig, referred to his 1936 publication as "The
Theory of Finite and Infinite Graphs" (translated from the German). The
results on graphs obtained during the time between Konigberg and Konig's
book were indeed developing into a theory. In the past several years a
number of changes have taken place in graph theory. The applicability of
graphs and graph theory to a wide range of areas both within and outside
mathematics has given added stature to this youthful subject. It is clear that
the full potential and usefulness of graph theory is only beginning to be
realized.
The growth of graph theory during its first two hundred years could in
no way foreshadow the spectacular progress which this area was to make.
There is little doubt that many of the early concepts and theorems (and a
few recent ones as well) were influenced by attempts to settle the Four
Color Conjecture. Undoubtedly, the development of graph theory was
favorably affected by the resistance to proof displayed by this now famous
theorem. No longer, however, is graph theory a subject which primarily
deals with the Four Color Conjecture or with games and puzzles. The
dynamic expansion of graph theory has lead to the development of many
significant and applicable subareas with its own concepts and theorems. As
with any other area of mathematics, each major theorem in graph theory
has associated with it an example or class of examples which illustrate the
necessity of the hypothesis, the sharpness of the result, or the falsity of the
converse. In this case, the examples are, of course, graphs. In many cases,
the graphs have become as famous as the theorems themselves. 