Second order differentiation formula on RCD*$(K,N)$ spaces
By Nicola Gigli, Luca Tamanini. Journal of the European Mathematical Society (Print), 2018
55 citations recorded by the source corpus.
Aim of this paper is to prove the second order differentiation formula for $H^{2,2}$ functions along geodesics in $RCD^*(K,N)$ spaces with $N < \infty$. This formula is new even in the context of Alexandrov spaces, where second order differentiation is typically related to semiconvexity. We establish this result by showing that $W_2$-geodesics can be approximated up to second order, in a sense which we shall make precise, by entropic interpolation. In turn this is achieved by proving new, even in the smooth setting, estimates concerning entropic interpolations which we believe are interesting on their own. In particular we obtain: - equiboundedness of the densities along the entropic interpolations, - local equi-Lipschitz continuity of the Schr\"odinger potentials, - a uniform weighted $L^2$ control of the Hessian of such potentials. Finally, the techniques adopted in this paper can be used to show that in the $RCD$ setting the viscous solution of the Hamilton-Jacobi equation can be obtained via a vanishing viscosity method, in accordance with the smooth case. With respect to a previous version, where the space was assumed to be compact, in this paper the second order differentiation formula is proved in full generality.
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Citations in the corpus
- Stability of entropic optimal transport and Schrödinger bridges (2021, background): “Convergence of potentials was shown in [29] for quadratic costs and compactly supported marginals, and recently in [41] for a general Polish setting.”
- Entropic optimal transport: convergence of potentials (2021, background): “We emphasize that [17] analyzes the more complex dynamic problem of approximating W2 geodesics with entropic interpolation; the present static setting would correspond only to its marginals at times t = 0, 1.”