Infinite dimensional manifolds, Lie groups and algebras arise naturally
in many areas of mathematics and physics. Having been used mainly as a
tool for the study of finite dimensional objects, the emphasis has
changed and they are now frequently studied for their own independent
interest. On the one hand this is a collection of closely related
articles on infinite dimensional Kähler manifolds and associated group
actions which grew out of a DMV-Seminar on the same subject. On the
other hand it covers significantly more ground than was possible during
the seminar in Oberwolfach and is in a certain sense intended as a
systematic approach which ranges from the foundations of the subject to
recent developments. It should be accessible to doctoral students and as
well researchers coming from a wide range of areas. The initial chapters
are devoted to a rather selfcontained introduction to group actions on
complex and symplectic manifolds and to Borel-Weil theory in finite
dimensions. These are followed by a treatment of the basics of infinite
dimensional Lie groups, their actions and their representations.
Finally, a number of more specialized and advanced topics are discussed,
e.g., Borel-Weil theory for loop groups, aspects of the Virasoro
algebra, (gauge) group actions and determinant bundles, and second
quantization and the geometry of the infinite dimensional Grassmann
manifold.