Abstract
Many investigations in the local differential geometry of surfaces focused on Gaussian curvature
and mean curvature. Besides these classical curvature invariants, are there any other geometric
quantities that deserve to be investigated? In the recent decades, there have been important
developments in the area of new curvature invariants for submanifolds, mostly included in Bang-
Yen Chen’s important monograph Pseudo-Riemannian geometry, δ−invariants and applications, World
Scientific, 2011. These developments are inviting us to look at the classical content from a different
perspective, exploring other quantities that might be of interest.