我们知道“空集”是集合中一种最主要也是最基本的集合,也是我们在描述周围现象中经常用到的集合,在数学中更是经常要用的。例如:所有不能表示为两个素数之和的偶数集合是空集吗?这就是哥德巴赫猜想。一般地说,集合常常被分为有限集合和无限集合两类。有限集合是含有有限元素的集合。像学校中人的集合,学校中男人的集合,学校中女人的集合,学校中老师 We know that “empty sets” are the most important and basic set of collections. They are also collections that we often use to describe surrounding phenomena. They are often used in mathematics. For example: Any even set that cannot be expressed as a sum of two prime numbers is an empty set? This is the Goldbach conjecture. In general, collections are often divided into finite collections and infinite collections. A finite set is a set containing finite elements. A collection of people like a school, a collection of men in a school, a collection of women in a school, a teacher in a school