convex set
A set in a vector space where, for any two points in the set, the line segment connecting them is also entirely contained in the set. Used in mathematics, especially in convex analysis and optimization.
To understand the definition of a convex set, you first need the concept of a vector space.
この問題では、実行可能領域が凸集合であることを示せ。
In this problem, show that the feasible region is a convex set.