Institution: | (1) Department of Mathematics, University of Oslo, P.O. Box 1053, Blindern, 0316 Oslo, Norway (e-mail: {fredb,kre}@math.uio.no) , NO;(2) Department of Mathematics, University of Bergen, Johs. Brunsgt. 12, 5008 Bergen, Norway (e-mail: kennethk@mi.uib.no) , NO |