convex set的用法和样例：
例句
- Convex sets and functions have many interesting and useful properties which are not explored in detail here.
凸集和凸函数具有很多重要的和有用的性质，在此不作详细讨论。 - Duality is emphasized throughout,particularly in the form of Fenchel's conjugacy correspondence for convex functions.
这本书的目的是为了提供各类凸集和凸函数理论的介绍，它们在极值问题的应用中发挥核心作用。
