Disjoint sets

In mathematics, two sets are disjoint when they have no elements in common. For example, the sets [math]\displaystyle{ \{1, 3\} }[/math] and [math]\displaystyle{ \{2, 4\} }[/math] are disjoint, but the sets [math]\displaystyle{ \{1, 3\} }[/math] and [math]\displaystyle{ \{1, 5\} }[/math] are not disjoint.