Characterization of Low Dimensional RCD*(K, N) Spaces

In this paper, we give the characterization of metric measure spaces that satisfy synthetic lower Riemannian Ricci curvature bounds (so called RCD*(K, N) spaces) with non-empty one dimensional regular sets. In particular, we prove that the class of Ricci limit spaces with Ric >= K and Hausdorff dimension N and the class of RCD*(K, N) spaces coincide for N < 2 (They can be either complete intervals or circles). We will also prove a Bishop-Gromov type inequality (that is, roughly speaking, a converse to the Lvy-Gromov's isoperimetric inequality and was previously only known for Ricci limit spaces) which might be also of independent interest.