When looking for applications of ring theory in geometry, one first
thinks of algebraic geometry, which sometimes may even be interpreted as
the concrete side of commutative algebra. However, this highly de-
veloped branch of mathematics has been dealt with in a variety of mono-
graphs, so that - in spite of its technical complexity - it can be
regarded as relatively well accessible. While in the last 120 years
algebraic geometry has again and again attracted concentrated interes-
which right now has reached a peak once more -, the numerous other
applications of ring theory in geometry have not been assembled in a
textbook and are scattered in many papers throughout the literature,
which makes it hard for them to emerge from the shadow of the brilliant
theory of algebraic geometry. It is the aim of these proceedings to give
a unifying presentation of those geometrical applications of ring theo y
outside of algebraic geometry, and to show that they offer a
considerable wealth of beauti- ful ideas, too. Furthermore it becomes
apparent that there are natural connections to many branches of modern
mathematics, e. g. to the theory of (algebraic) groups and of Jordan
algebras, and to combinatorics. To make these remarks more precise, we
will now give a description of the contents. In the first chapter, an
approach towards a theory of non-commutative algebraic geometry is
attempted from two different points of view.