Author Archives: Fabrice Baudoin

Lecture 20. Upper and lower heat kernel Gaussian bounds

In this short Lecture, as in the previous one, we consider a complete and -dimensional Riemannian manifold with non negative Ricci curvature. The volume doubling property that was proved is closely related to sharp lower and upper Gaussian bounds that … Continue reading

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Lecture 19. Volume doubling property

In this Lecture we consider a complete and -dimensional Riemannian manifold with non negative Ricci curvature. Our goal is to prove the following fundamental result, which is known as the volume doubling property. Theorem: There exists a constant such that … Continue reading

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Richard Courant: From Göttingen to New-York.

An interesting look into the life and career of Richard Courant:

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Curvature inequalities in sub-Riemannian geometry

An important part of my research from the past few years has been to try to understand the notion of Ricci curvature lower bound in sub-Riemannian geometry. On this problem, my point of view is more the one of an … Continue reading

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Lecture 18. The Gaussian upper bound for the heat kernel

Let be a complete -dimensional Riemannian manifold and, as usual, denote by its Laplace-Beltrami operator. As in the previous lecture, we will assume that the Ricci curvature of is bounded from below by with . Our purpose in this lecture … Continue reading

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Lecture 17. The parabolic Harnack inequality

Let be a complete -dimensional Riemannian manifold and, as usual, denote by its Laplace-Beltrami operator. Throughout the Lecture, we will assume that the Ricci curvature of is bounded from below by with . Our purpose is to prove a first … Continue reading

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Lecture 16. The Li-Yau inequality

Let be a complete -dimensional Riemannian manifold and, as usual, denote by its Laplace-Beltrami operator. Throughout the Lecture, we will assume again that the Ricci curvature of is bounded from below by . The Lecture is devoted to the proof … Continue reading

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Lecture 15. Convergence of the semigroup, Poincare and log-Sobolev

Let be a complete -dimensional Riemannian manifold and denote by its Laplace-Beltrami operator. As usual, we denote by the heat semigroup generated by . Throughout the Lecture, we will assume that the Ricci curvature of is bounded from below by … Continue reading

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Lecture 14. Stochastic completeness of the heat semigroup

In this Lecture, we will prove a first interesting consequence of the Bochner’s identity: We will prove that if, on a complete Riemannian manifold , the Ricci curvature is bounded from below, then the heat semigroup is stochastically complete, that … Continue reading

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Lecture 13. The Bochner’s formula

The goal of this lecture is to prove the Bochner formula: A fundamental formula that relates the so-called Ricci curvature of the underlying Riemannian structure to the analysis of the Laplace–Beltrami operator. The Bochner’s formula is a local formula, we … Continue reading

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