Event

Sang-hyun Kim, Seoul National University

Wednesday, September 27, 2017 15:00to16:00
Burnside Hall Room 920, 805 rue Sherbrooke Ouest, Montreal, QC, H3A 0B9, CA

Free products in Diff(S1)

We prove that if G is a finitely generated non-virtually-abelian group, then (G x Z) * Z does not embed into Diff^2(S^1). In particular, the class of subgroups of Diff^r(S^1) is not closed under taking free products for each r >= 2. We complete the classification of RAAGs embeddable in Diff^r(S^1) for each r, answering a question in a paper of M. Kapovich. (Joint work with Thomas Koberda)
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