Synthetic versus distributional lower Ricci curvature bounds

We compare two standard approaches to defining lower Ricci curvature bounds for Riemannian metrics of regularity below $C<^>2$. These are, on the one hand, the synthetic definition via weak displacement convexity of entropy functionals in the framework of optimal transport, and the distributional one based on non-negativity of the Ricci-tensor in the sense of Schwartz. It turns out that distributional bounds imply entropy bounds for metrics of class $C<^>1$ and that the converse holds for $C<^>{1,1}$-metrics under an additional convergence condition on regularizations of the metric.

Automated summary

We compare two standard approaches to defining lower Ricci curvature bounds for Riemannian metrics of regularity below $C<^>2$.