Evolution variational inequalities with general costs
Pierre-Cyril Aubin-Frankowski, Giacomo Enrico Sodini, Ulisse Stefanelli
TL;DR
The paper develops Evolution Variational Inequalities (EVIs) driven by general costs $c$ on general sets, extending gradient-flow theory beyond metric spaces. It establishes equivalences among differential, integral, and exponential-integral EVI formulations, proves contraction and energy identities, and provides local slope characterizations under compatibility conditions. Existence of EVI flows is shown as the limit of splitting schemes based on the $c$-transform, with both implicit and explicit iterations analyzed under cross-convexity and NNCC-type assumptions. The framework encompasses classical costs like $c=d^p$, KL divergence, and Sinkhorn divergences, enabling new gradient-flow-type evolutions in non-metric settings with entropic and Bregman structures. This yields a versatile toolbox for analyzing evolution in measures and other spaces where nonmetric costs govern the dynamics, with concrete schemes and convergence guarantees bridging discrete approximations to continuous EVI flows.
Abstract
We extend the theory of gradient flows beyond metric spaces by studying evolution variational inequalities (EVIs) driven by general cost functions $c$, including Bregman and entropic transport divergences. We establish several properties of the resulting flows, including stability and energy identities. Using novel notions of convexity related to costs $c$, we prove that EVI flows are the limit of splitting schemes, providing assumptions for both implicit and explicit iterations.
