Calculus of Variations and Geometric Measure Theory

L. Ambrosio - N. Gigli - G. Savaré

Heat flow and calculus on metric measure spaces with Ricci curvature bounded below - the compact case

created by savare on 15 May 2012



Inserted: 15 may 2012
Last Updated: 15 may 2012

Year: 2012

To the memory of Enrico Magenes, whose exemplar life, research and teaching shaped generations of mathematicians.


We provide a quick overview of various calculus tools and of the main results concerning the heat flow on compact metric measure spaces, with applications to spaces with lower Ricci curvature bounds.

Topics include the Hopf-Lax semigroup and the Hamilton-Jacobi equation in metric spaces, a new approach to differentiation and to the theory of Sobolev spaces over metric measure spaces, the equivalence of the $L^2$-gradient flow of a suitably defined ``Dirichlet energy'' and the Wasserstein gradient flow of the relative entropy functional, a metric version of Brenier's Theorem, and a new (stronger) definition of Ricci curvature bound from below for metric measure spaces. This new notion is stable w.r.t. measured Gromov-Hausdorff convergence and it is strictly connected with the linearity of the heat flow.

Keywords: Optimal transport, entropy, Ricci curvature, Heat Flow