DEFINITION 1 80t8 集合 The objects in a set are also called the elements or members of the set, a set is said to contain its elements Null Set: There are no anything in the set O={x|x∈P(x)∧~(x∈P(x)) 2/24/202111:15PM Deren Chen Zhejiang univ 3S e t s 集合 2/24/2021 11:15 PM Deren Chen, Zhejiang Univ. 3 DEFINITION 1. The objects in a set are also called the elements, or members, of the set. A set is said to contain its elements. Null Set: There are no anything in the set. Ø={x | xP(x) ∧ (x P(x) )}