I am indebted to many persons and ideas, to make a thorough list would be impossible. That does however not prevent me from expressing my gratitude, to my supervisor Cecilia Jarlskog, and to the Department of Mathematical Physics, where it has been a pleasure to work.
I thank my daughters, Toiko and Snøfrid Kleppe, for one day reading at least sections 1 and 2 in the introduction, which were written with them in mind; and for continuously keeping me in touch with essential matters. I also want to thank Holger Bech Nielsen, Henning Braaten, Love Lappalainen and Tõnis Tõnisson, for useful discussions with different angles of incidence.
Special thanks are due to
Ingemar Bengtsson and Conrad Newton, who have helped me by endless discussions
and fruitful suggestions.
Lund in April 1997