Set Intersection

The intersection of two sets consists of all of the elements that the two sets have in common. The intersection set is a proper subset of both the originating sets. If the sets are disjointed sets then there are no elements in common between them and the intersection is the empty set. The intersection of more than two sets can be found by intersecting two sets and then intersecting the resulting set with the third set and so forth. The associative law and the commutative law for sets state that it does not matter which two sets are taken first or in what order they are taken. The intersection of two sets is different from the union of two sets in that either set can contain the element for it to be in the set union.

The intersection of the set of numbers (1, 2, 3, 4) and the set of numbers (3, 4, 5, 6) is the set (3, 4).

The intersection of the set of numbers (1, 2, 3, 4) and the set of numbers (5, 6, 7, 8) is (the empty set).