# $L^1$-gradient flow of convex functionals

## TL;DR

This paper studies the gradient flow of convex functionals in the $L^1$ topology, establishing existence, uniqueness under certain conditions, and analyzing geometric evolution related to anisotropic perimeter and convex sets.

## Contribution

It introduces an implicit minimization scheme for $L^1$-gradient flows, proves existence and uniqueness of solutions under strong convexity and monotonicity assumptions, and explores geometric evolution of convex sets.

## Key findings

- Existence of global limit solutions for the $L^1$-gradient flow.
- Uniqueness of solutions under strong convexity and monotonicity assumptions.
- Monotone, convex, and unique evolution until reaching the Cheeger set in the geometric case.

## Abstract

We are interested in the gradient flow of a general first order convex functional with respect to the $L^1$-topology. By means of an implicit minimization scheme, we show existence of a global limit solution, which satisfies an energy-dissipation estimate, and solves a non-linear and non-local gradient flow equation, under the assumption of strong convexity of the energy. Under a monotonicity assumption we can also prove uniqueness of the limit solution, even though this remains an open question in full generality. We also consider a geometric evolution corresponding to the $L^1$-gradient flow of the anisotropic perimeter. When the initial set is convex, we show that the limit solution is monotone for the inclusion, convex and unique until it reaches the Cheeger set of the initial datum. Eventually, we show with some examples that uniqueness cannot be expected in general in the geometric case.