In order to determine or establish convexity of sets, it is useful to review some operators that preserve the convexity....
Cone and convex cone. A set $C\subseteq\mathbb R^n$ is called a cone if for every $x\in C$ and $\lambda\geqslant 0$...
Affine sets A set $C\subseteq\mathbb R^n$ is affine if the line through any two points in $C$ lies in $C$....