Curvature bounds by isoperimetric comparison for normalized Ricci flow on the two-sphere

Springer Science and Business Media LLC - Tập 39 - Trang 419-428 - 2010
Ben Andrews1, Paul Bryan2
1Centre for Mathematics and its Applications, Australian National University, Canberra, Australia
2Department of Mathematics, Australian National University, Canberra, Australia

Tóm tắt

We prove a comparison theorem for the isoperimetric profiles of solutions of the normalized Ricci flow on the two-sphere: If the isoperimetric profile of the initial metric is greater than that of some positively curved axisymmetric metric, then the inequality remains true for the isoperimetric profiles of the evolved metrics. We apply this using the Rosenau solution as the model metric to deduce sharp time-dependent curvature bounds for arbitrary solutions of the normalized Ricci flow on the two-sphere. This gives a simple and direct proof of convergence to a constant curvature metric without use of any blowup or compactness arguments, Harnack estimates, or any classification of behaviour near singularities.

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