Abstract
We prove that the only closed, embedded ancient solutions to the curve shortening flow on S2 are equators or shrinking circles, starting at an equator at time t = -∞ and collapsing to the north pole at time t = 0. To obtain the result, we first prove a Harnack inequality for the curve shortening flow on the sphere. Then an application of the Gauss–Bonnet, easily allows us to obtain curvature bounds for ancient solutions leading to backwards smooth convergence to an equator. To complete the proof, we use an Aleksandrov reflection argument to show that maximal symmetry is preserved under the flow.
Original language | English |
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Pages (from-to) | 858-872 |
Number of pages | 15 |
Journal | Journal of Geometric Analysis |
Volume | 26 |
Issue number | 2 |
DOIs | |
Publication status | Published - Apr 2016 |
Externally published | Yes |
Keywords
- Curve shortening flow
- Ancient solutions
- Aleksandrov reflection
- Harnack