Hamilton’s gradient estimate for the heat kernel on complete manifolds

Kotschwar, Brett

doi:10.1090/S0002-9939-07-08837-5

Hamilton’s gradient estimate for the heat kernel on complete manifolds
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by Brett L. Kotschwar PDF

Proc. Amer. Math. Soc. 135 (2007), 3013-3019 Request permission

Abstract:

In this paper we extend a gradient estimate of R. Hamilton for positive solutions to the heat equation on closed manifolds to bounded positive solutions on complete, non-compact manifolds with $Rc \geq -Kg$. We accomplish this extension via a maximum principle of L. Karp and P. Li and a Berstein-type estimate on the gradient of the solution. An application of our result, together with the bounds of P. Li and S.T. Yau, yields an estimate on the gradient of the heat kernel for complete manifolds with non-negative Ricci curvature that is sharp in the order of $t$ for the heat kernel on ${\mathbb {R}}^n$.

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