pleasant introduction on a variety of topics about Lie groups, homo-
geneous spaces and related applications.
I would like to express my sincere thanks to the editors for their
thorough suggestions on the manuscript, as well as my gratitude to
Professors Jurgen Berndt, Martin A. Guest, Lieven Vanhecke, and
McKenzie Y. Wang for their kindness in making comments on it.
Athens, August 2003