TY - JOUR TI - Twice Differentiable Characterizations of Convexity Notions for Functions on Full Dimensional Convex Sets AU - Stein, Oliver TI - Twice Differentiable Characterizations of Convexity Notions for Functions on Full Dimensional Convex Sets AB - 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. VL - 2012 IS - Volume 21 PY - 2012 SN - 1732-3916 C1 - 2083-8476 SP - 55 EP - 63 DO - 10.4467/20838476SI.12.004.0814 UR - https://ejournals.eu/en/journal/schedae-informaticae/article/twice-differentiable-characterizations-of-convexity-notions-for-functions-on-full-dimensional-convex-sets KW - true convexity KW - differentiable characterization KW - full dimensional convex set. KW - convexity KW - strict convexity KW - strong convexity