V. Balestro, H. Martini and R. Teixeira, Surface immersions in normed spaces from the affine point of view, to appear in Geometriae Dedicata, 2018. (arXiv link) (journal link)
Comments: We’ve wrote a paper developing curvature concepts for surfaces immersed in three-dimensional spaces endowed with a norm (principal curvatures, Gaussian and mean curvatures, normal curvature). It turns out that the idea to do so came from affine differential geometry, and hence we naturally had a lot of questions related to this area within our context. We study affine distance functions, and from this we re-obtain some curvature concepts and also prove some rigidity theorems. We also introduce a Riemannian metric which is closely related to the induced geometry of the surface. Finally, we show in which cases the Birkhoff-Gauss map of a surface is the Blaschke vector field.