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arXiv · 1605.09240

Extremals of Log Sobolev inequality on non-compact manifolds and Ricci soliton structures

Michele Rimoldi·Giona Veronelli
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Abstract

In this paper we establish the existence of extremals for the Log Sobolev functional on complete non-compact manifolds with Ricci curvature bounded from below and strictly positive injectivity radius, under a condition near infinity. When Ricci curvature is also bounded from above we get exponential decay at infinity of the extremals. As a consequence of these analytical results we establish, under the same assumptions, that non-trivial shrinking Ricci solitons support a gradient Ricci soliton structure. On the way, we prove two results of independent interest: the existence of a distance-like function with uniformly controlled gradient and Hessian on complete non-compact manifolds with bounded Ricci curvature and strictly positive injectivity radius and a general growth estimate for the norm of the soliton vector field on manifolds with bounded Ricci curvature.

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Michele Rimoldi, Giona Veronelli. 2016-05-30. Extremals of Log Sobolev inequality on non-compact manifolds and Ricci soliton structures. https://doi.org/10.1007/s00526-019-1518-z

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