1, the intersection of two or more sets in mathematics, that is, the quantity that belongs to several sets or satisfies several conditions at the same time.
2. The intersection of A and B is written as A ∩ B. Formally, X belongs to A ∩ B. For example, the intersection of sets {1, 3,7} and {2,3,7} is {3,7}. If the intersection of two sets A and B is empty, that is, they have no common elements, then they do not intersect, so there is no intersection.
3. Set operation: commutative law: A∩B=B∩A, A ∪ B = B ∪ A
Law of association: (A∩B)∩C=A∩(B∩C), (A∪B)∪C=A∪(B∪C).
Distribution law: A∩(B∪C)=(A∪B)∩(A∪C), A ∪( B∪C)=(A∪B)∩(A∪.