Another terminology question:
If a function $f(x)$ is strictly convex at $y$, does this mean, for an already convex function:
a) $f'(y) = 0$, or equally, $y = \arg \min_y f(y)$
b) $f''(x) \geq 0$ and $f''(y) \neq 0$
c) Something else (specify)
Thanks, L
EDIT: Where $f(x)$ is not differentiable at $x$, read $f'(x)$ as the subgradient of $f$ at $x$. i.e. $f'(x)=0$ means that for subgradient [a,b], $a \leq 0$, $b \geq 0$. Similarly for $f''$.