Topological and dynamical obstructions to extending group actions.
1 hour 1 min,
236.48 MB,
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About this item
| Description: |
Nariman, S
Friday 7th December 2018 - 11:30 to 12:30 |
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| Created: | 2018-12-10 09:57 |
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| Collection: | Higher structures in homotopy theory |
| Publisher: | Isaac Newton Institute |
| Copyright: | Nariman, S |
| Language: | eng (English) |
| Distribution: |
World
(downloadable)
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| Explicit content: | No |
| Aspect Ratio: | 16:9 |
| Screencast: | No |
| Bumper: | UCS Default |
| Trailer: | UCS Default |
| Abstract: | For any 3-manifold M with torus boundary, we find finitely generated subgroups of \Diff0(∂M) whose actions do not extend to actions on M; in many cases, there is even no action by homeomorphisms. The obstructions are both dynamical and cohomological in nature. We also show that, if ∂M=S2, there is no section of the map \Diff0(M)→\Diff0(∂M). This answers a question of Ghys for particular manifolds and gives tools for progress on the general program of bordism of group actions. This is a joint work with Kathryn Mann. |
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