Quasiconvexity in the Riemannian setting
Aurora Corbisiero, Chiara Leone, Carlo Mantegazza
TL;DR
The paper addresses extending the classical Morrey–Acerbi–Fusco theory of quasiconvexity and lower semicontinuity from Euclidean spaces to the Riemannian setting. It introduces a Riemannian notion of quasiconvexity for functions on the bundle $\mathscr{L}(TM,\mathbb{R}^m)$, employing an exponential-map-based transport and a vanishing correction term to compare perturbations at a fixed tangent space. The authors prove an equivalence: $f$ is Riemannian quasiconvex if and only if the integral functional $F(u,\Omega)=\int_{\Omega} f(du)\,d\mu$ is sequentially lower semicontinuous with respect to the weak$^*$ topology on $W^{1,\infty}(\Omega,\mathbb{R}^m)$ for every open bounded $\Omega\subset M$, effectively generalizing Acerbi–Fusco to the Riemannian context. They also outline future directions, including extensions to $W^{1,p}$, integration with manifold-valued map results, and the development of additional convexity notions on manifolds.
Abstract
We introduce a notion of quasiconvexity for continuous functions $f$ defined on the vector bundle of linear maps between the tangent spaces of a smooth Riemannian manifold $(M,g)$ and $\mathbb{R}^m$, naturally generalizing the classical Euclidean definition. We prove that this condition characterizes the sequential lower semicontinuity of the associated integral functional \[ F(u, Ω) = \int_Ω f(du) \, dμ\] with respect to the weak$^*$ topology of $W^{1,\infty}(Ω, \mathbb{R}^m)$, for every bounded open subset $Ω\subseteq M$.
