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xii Preface to the German Edition

Dr. Christof Eck, Alexander Prechtel, Joachim Rang, and Dr. Eckhard
Schneid did the proofreading and suggested important improvements. From
the anonymous referees we received useful comments. Very special thanks
go to Mrs. Magdalena Ihle and Dr. Gerhard Summ. Mrs. Ihle transposed
the text quickly and precisely into T X. Dr. Summ not only worked on the
E
original script and on the T X-form, he also organized the complex and
E
distributed rewriting and extension procedure. The elimination of many
inconsistencies is due to him. Additionally he influenced parts of Sec-
tions 3.4 and 3.8 by his outstanding diploma thesis. We also want to thank
Dr. Chistoph Tapp for the preparation of the graphic of the title and for
providing other graphics from his doctoral thesis [70].
Of course, hints concerning (typing) mistakes and general improvements
are always welcome.
We thank Springer-Verlag for their constructive collaboration.
Last, but not least, we want to express our gratitude to our families for
their understanding and forbearance, which were necessary for us especially
during the last months of writing.

Erlangen, Germany Peter Knabner
Magdeburg, Germany Lutz Angermann
February 2000