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visits | member for | 3 years, 1 month |
seen | Apr 14 at 18:31 | |
stats | profile views | 2,028 |
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Apr 8 |
accepted | Fundamental group of a manifold with an $S^1$-action |
Apr 8 |
comment |
Fundamental group of a manifold with an $S^1$-action
Igor, I will accept your answer. I think indeed, that explicit counterexamples can be constructed for example as follows. Take the linear S^1 action on S^3 that fixes $S^1$. Then the quotient is $D^2$. Now take as many $S^1$ fibers in $S^3$ as you want and make a Dehn surgery at these fibres. Then the quotient will become a disk with orbi-points, and I guess the obrifold fundamental group of the disk will be related to the fundamental group of the surgered $3$-manifold. Would you agree with this? |
Apr 8 |
comment |
Fundamental group of a manifold with an $S^1$-action
Thank you Igor! I will check the paper once I wake up :) |
Apr 8 |
comment |
Fundamental group of a manifold with an $S^1$-action
Francesco, thank you for this example. I amended the question to ask if at least the kernel of the map is finite. This is what I really want... |
Apr 8 |
revised |
Fundamental group of a manifold with an $S^1$-action
added 173 characters in body |
Apr 8 |
comment |
Fundamental group of a manifold with an $S^1$-action
Thank you, indeed, this is a counterexample. I amended the question, because I was asking for more than I really need. |
Apr 7 |
asked | Fundamental group of a manifold with an $S^1$-action |
Mar 27 |
awarded | Necromancer |
Mar 5 |
awarded | Yearling |
Feb 26 |
comment |
Image of a hypersurface under a map $\mathbb CP^n\to \mathbb CP^n$
Jason, thank you for this comment, you are right of course. |
Feb 26 |
revised |
Image of a hypersurface under a map $\mathbb CP^n\to \mathbb CP^n$
added 12 characters in body |
Feb 25 |
asked | Image of a hypersurface under a map $\mathbb CP^n\to \mathbb CP^n$ |
Feb 21 |
comment |
Easy to state applications of dimension theory in algebraic geometry
ACL, sure I had in mind the non-algebraic action. I can not yet grasp why dimension theory is doing the job in the algebraic case (while it fails in the analytic case)... |
Feb 21 |
comment |
Easy to state applications of dimension theory in algebraic geometry
Daniel, thank you for this answer. I am not quite sure though that I understand the phrase in grey. For example $\mathbb C^*$ is acting on an any elliptic curve over $\mathbb C$, and the action is without fixed points. |
Feb 21 |
asked | Easy to state applications of dimension theory in algebraic geometry |
Feb 21 |
accepted | Extending the tautological bundle of $G(1,3)$? |
Feb 21 |
comment |
Extending the tautological bundle of $G(1,3)$?
Alex, I think your reasoning is correct. Could you give me a reference to some nice book that explains that tautological Chern classes generate $H^*$ of the Grassmanian? |
Feb 21 |
revised |
Extending the tautological bundle of $G(1,3)$?
edited body |
Feb 21 |
asked | Extending the tautological bundle of $G(1,3)$? |
Feb 14 |
comment |
Sufficient conditions for a divisor to be connected on a K3 surface
In fact after I wrote this answer I realised that the first comment of Artie solves the problem. |