%0 Journal Article %T Twice Differentiable Characterizations of Convexity Notions for Functions on Full Dimensional Convex Sets %A Stein, Oliver %J Schedae Informaticae %V 2012 %R 10.4467/20838476SI.12.004.0814 %N Volume 21 %P 55-63 %K true convexity, differentiable characterization, full dimensional convex set., convexity, strict convexity, strong convexity %@ 1732-3916 %D 2012 %U https://ejournals.eu/en/journal/schedae-informaticae/article/twice-differentiable-characterizations-of-convexity-notions-for-functions-on-full-dimensional-convex-sets %X IWe derive C2 −characterizations for convex, strictly convex, as well as strongly convex functions on full dimensional convex sets. In the cases of convex and strongly convex functions this weakens the well-known openness assumption on the convex sets. We also show that, in a certain sense, the full dimensionality assumption cannot be weakened further. In the case of strictly convex functions we weaken the well-known sufficient C2 −condition for strict convexity to a characterization. Several examples illustrate the results.