Intersection: in set theory, let A and B be two sets, and the set composed of all elements belonging to set A and set B is called the intersection of set A and set B, and it is marked as A ∩ B.

Union set: given two sets A and B, the set formed by merging all their elements is called the union set of set A and set B, marked as A∪B, and pronounced as A and B.

Extended data:

Algebraic properties of union sets;

Binary union (union of two sets) is a combination operation, that is, A ∨( B∪C)=(A∪B)∪C, in fact, A∪B∪C is also equal to these two sets, so parentheses can be omitted when only union operation is performed. Similarly, the union operation satisfies the commutative law, that is, the order of the sets is arbitrary.

Empty set is the unit element of union operation. Namely. ∪A=A = A. For any set A, an empty set can be regarded as the union of zero sets.

Joint operation combines intersection operation and complement set operation, and integrates any power into Boolean algebra. For example, union and intersection satisfy the distribution law, and these three operations satisfy De Morgan's law. If the union operation is replaced by symmetric difference operation, the corresponding Boolean ring can be obtained.

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