AbstractIn this article, a proof of the interpolation inequality along geodesics
in p-Wasserstein spaces is given. This interpolation inequality
was the main ingredient to prove the Borel–Brascamp–Lieb inequality
for general Riemannian and Finsler manifolds and led Lott–Villani
and Sturm to define an abstract Ricci curvature condition. Following
their ideas, a similar condition can be defined and for positively
curved spaces one can prove a Poincaré inequality. Using Gigli’s
recently developed calculus on metric measure spaces, even a q-Laplacian
comparison theorem holds on q-infinitesimal convex spaces.
In the appendix, the theory of Orlicz–Wasserstein spaces is developed
and necessary adjustments to prove the interpolation inequality along
geodesics in those spaces are given.