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On the equivalence of distributional and synthetic Ricci curvature lower bounds

Andrea Mondino, Vanessa Ryborz

TL;DR

The paper proves an equivalence between distributional and synthetic lower bounds for Bakry–Émery Ricci curvature on weighted manifolds with a continuous metric and low-regularity connections. It develops a comprehensive non-smooth calculus, including a weak Bochner formula, and establishes a robust first- and second-order framework that aligns distributional Ricci bounds with the RCD/CD notions via BE inequalities. The main contributions are (i) showing that $\mathsf{RCD}^*(K,N)$ (or $\mathsf{RCD}(K,\infty)$) implies a distributional $\mathrm{Ric}_{\mu,N}\ge K g$ and (ii) proving the reverse implication under a volume-growth condition, thereby unifying distributional and synthetic curvature notions on spaces with low regularity. This bridges classical geometric analysis with modern metric-measure theory, enabling curvature-based methods on spaces with minimal smoothness and weighted measures.

Abstract

The goal of the paper is to prove the equivalence of distributional and synthetic Ricci curvature lower bounds for a weighted Riemannian manifold with continuous metric tensor having Christoffel symbols in $L^2_{\rm loc}$, and with weight in $C^0\cap W^{1,2}_{\rm loc}$.

On the equivalence of distributional and synthetic Ricci curvature lower bounds

TL;DR

The paper proves an equivalence between distributional and synthetic lower bounds for Bakry–Émery Ricci curvature on weighted manifolds with a continuous metric and low-regularity connections. It develops a comprehensive non-smooth calculus, including a weak Bochner formula, and establishes a robust first- and second-order framework that aligns distributional Ricci bounds with the RCD/CD notions via BE inequalities. The main contributions are (i) showing that (or ) implies a distributional and (ii) proving the reverse implication under a volume-growth condition, thereby unifying distributional and synthetic curvature notions on spaces with low regularity. This bridges classical geometric analysis with modern metric-measure theory, enabling curvature-based methods on spaces with minimal smoothness and weighted measures.

Abstract

The goal of the paper is to prove the equivalence of distributional and synthetic Ricci curvature lower bounds for a weighted Riemannian manifold with continuous metric tensor having Christoffel symbols in , and with weight in .
Paper Structure (21 sections, 60 theorems, 332 equations)

This paper contains 21 sections, 60 theorems, 332 equations.

Key Result

Theorem 1

Let $M$ be a smooth manifold, $g$ a continuous Riemannian metric with Christoffel symbols in $L^2_{\rm{loc}}$, and $V \in C^{0}\cap W^{1,2}_{\rm{loc}}(M)$ a positive function on $M$. Define the weighted measure $\mu$ as ${\rm d}\mu:= e^{-V}{\rm d}\mathrm{vol}_g$. Let $N \in [n, \infty]$ and $K \in

Theorems & Definitions (125)

  • Theorem 1: see Theorem \ref{['equivalence_result']}
  • Remark 1.1: On the smoothness assumption on $M$
  • Remark 1.2: On the volume growth assumption
  • Definition 2.1: Action of a vector field on a distribution, lefloch2007definition
  • Definition 2.2: lefloch2007definition, Def. 4.1
  • Definition 2.3
  • Lemma 2.4
  • proof
  • Lemma 2.5: A Friedrichs type lemma
  • proof
  • ...and 115 more