👉 In mathematics, a jointlessness or null join of two sets is an operation that returns a set containing only the elements which are common to both input sets. For example, in the set {1, 2, 3}, if we define the union of {1, 2} and {3} as {1, 2, 3}, then this operation results in a set containing {1, 2}. Similarly, the intersection of {1, 2} and {