The work reported in this thesis was carried out in the Neural Networks Research Centre, Helsinki University of Technology, during 1996-2000. The work was mainly funded by the Helsinki Graduate School of Computer Science and Engineering. Additional support came from Jenny and Antti Wihuri Foundation.
I wish to thank Professors Juha Karhunen and Erkki Oja for supervising my work and Academy Professor Teuvo Kohonen for guiding the early steps of my scientific career and teaching me what scientific research is about.
I also wish to thank the co-authors of the publications included in this thesis, Xavier Giannakopoulos, James Miskin, Antti Honkela and Dr. Petteri Pajunen, as well as Juha Reunanen who did much of the preliminary experimental work for the last publication.
The manuscript of this thesis was reviewed by Professor Mark Girolami and Dr. Petri Myllymäki. I am grateful for their expert comments on the structure and scientific content which led to considerable improvements of the thesis. I also wish to express my sincere gratitude for the valuable comments and constructive criticism Professors Juha Karhunen and Erkki Oja gave on the earlier versions of the manuscript.
Special thanks go to the personnel of the Neural Networks Research Centre and the Laboratory of Computer and Information Science who have created a friendly and inspiring atmosphere in which to work.
I thank Lotta for her patience and tolerance during the time of writing the manuscript.
Espoo, October 2000