2 problems

Let $L$ be a convex function on ${\mathbb R}^n$, let $L'(x,\theta)$ denote its directional derivative at $x$ in the direction $\theta$, and define … where $\sigma_{n-1}$ is the uni…

Let $X$ be the domain of a Lipschitzian function $F:X\to\mathbb{R}$, and let $\nabla F(\boldsymbol{x})$ denote the set of subgradients of $F$ at $\boldsymbol{x}$. For…