Geometry Date:  Friday, March 15, 2013 Location:  3096 East Hall (3:00 PM to 4:00 PM) Title:  Surface quotients of hyperbolic buildings Abstract:   Bourdon's building is a negatively curved 2-complex built out of hyperbolic right-angled polygons. Its automorphism group is large (uncountable) and remarkably rich. We study, and mostly answer, the question of when there is a discrete subgroup of the automorphism group such that the quotient is a closed surface of genus g. This involves some fun elementary combinatorics, but quickly leads to open questions in group theory and number theory. One consequence of our construction is that a lattice in the automorphism group of Bourdon's building always contains a surface subgroup. This proves a special case of Gromov's surface subgroup conjecture. Joint work with Anne Thomas. Speaker:  Dave Futer Institution:  Temple Event Organizer:   Spatzier      Edit this event (login required). Add new event (login required). For access requests and instructions, contact math-webmaster@umich.edu Back to previous page Back to UM Math seminars/events page.