Trends in Mathematics Trends in Mathematics is a series devoted to the publication of volumes arising from conferences and lecture series focusing on a particular topic from any area of mathematics. Its aim is to make current developments available to the community as rapidly as possible without compromise to quality and to archive these for reference. Proposals for volumes can be sent to the Mathematics Editor at either Springer Basel AG Birkhäuser P.O. Box 133 CH-4010 Basel Switzerland or Birkhauser Boston 233 Spring Street New York, NY 10013 USA Material submitted for publication must be screened and prepared as follows: All contributions should undergo a reviewing process similar to that carried out by journals and be checked for correct use of language which, as a rule, is English. Articles without proofs, or which do not contain any significantly new results, should be rejected. High quality survey papers, however, are welcome. We expect the organizers to deliver manuscripts in a form that is essentially ready for direct reproduction. Any version of TeX is acceptable, but the entire collection of files must be in one particular dialect of TeX and unified according to simple instructions available from Birkhäuser. Furthermore, in order to guarantee the timely appearance of the proceedings it is essential that the final version of the entire material be submitted no later than one year after the conference. The total number of pages should not exceed 350. The first-mentioned author of each article will receive 25 free offprints. To the participants of the congress the book will be offered at a special rate. Combinatorial and Geometric Group Theory Dortmund and Ottawa-Montreal Conferences Oleg Bogopolski Inna Bumagin Olga Kharlampovich Enric Ventura Editors Birkhäuser Editors: Oleg Bogopolski Mathematisches Institut der Heinrich-Heine-Universität Düsseldorf Universitätsstr. 1 40225 Düsseldorf Germany e-mail:
[email protected] Olga Kharlampovich Department of Mathematics and Statistics McGill University 805 Sherbrooke St., West Montreal, Quebec, H3A 2K6 Canada e-mail:
[email protected] Inna Bumagin School of Mathematics and Statistics Carleton University 1125 Colonel By Drive Ottawa, Ontario, K1S 5B6 Canada e-mail:
[email protected] Enric Ventura Departament de Matematica Aplicada III EPSEM – Universitat Politècnica de Catalunya Av. Bases de Manresa 61–73 08242 Manresa, Barcelona Spain e-mail:
[email protected] 2000 Mathematics Subject Classification 20A, 20E, 20F, 20H, 20M, 20P, 03B, 03D, 05C, 08A, 51F, 57M, 57S, 60B, 68Q Library of Congress Control Number: 2010926413 Bibliographic information published by Die Deutsche Bibliothek. Die Deutsche Bibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data is available in the Internet at http://dnb.ddb.de ISBN 978-3-7643-9910-8 This work is subject to copyrig