DEFINITION 3 80t8 集合 The set a is said to be a subset of B if and only if every element of a is also an element of B. we use the notation acb to indicate that a is a subset of the set B A是B的子集、 B包含A、 A包含在B中 2/24/202111:15PM Deren Chen Zhejiang univS e t s 集合 2/24/2021 11:15 PM Deren Chen, Zhejiang Univ. 9 DEFINITION 3. The set A is said to be a subset of B if and only if every element of A is also an element of B. We use the notation AB to indicate that A is a subset of the set B. A是B的子集、 B包含A、 A包含在B中