Timeline for Remove a disc from a manifold. When is the resulting sphere nullhomotopic?
Current License: CC BY-SA 3.0
5 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jun 17, 2021 at 16:13 | comment | added | Michael Albanese | @WhySee: The top homology of a connected manifold is $\mathbb{Z}$ if it is closed and orientable, and zero otherwise. | |
| Apr 29, 2021 at 12:07 | comment | added | WhySee | Can I ask a potentially silly question? Using the Mayer-Vietoris sequence, we also get $\tilde{H}_n(M) \cong \tilde{H}_n(M \setminus D^{\circ}) \oplus \mathbb{Z}$, right? But why is $\tilde{H}_n(M\setminus D^{\circ})=0$? I can see that for surfaces, but having some difficulty seeing it in general. Thank you! | |
| Oct 2, 2017 at 18:35 | vote | accept | Michael Albanese | ||
| Sep 29, 2017 at 20:46 | answer | added | Oscar Randal-Williams | timeline score: 9 | |
| Sep 29, 2017 at 19:30 | history | asked | Michael Albanese | CC BY-SA 3.0 |