Heat flow for harmonic maps from graphs into Riemannian manifolds

We introduce the notion of harmonic map from a graph into a Riemannian manifold via a discrete version of the energy density. Existence and basic properties are established. Global existence and convergence of the associated heat flow are proved without any assumption on the curvature of the target manifold. We discuss a variant of the Steiner problem which replaces length by elastic energy. (c) 2022 Elsevier B.V. All rights reserved.