The complementary event A′ to an event A is the event ‘A does not occur’. It satisfies A ⋃ A′=S, where S is the sample space, and A ∩ A′=ϕ, where ϕ is the empty set. The complements of intersections and unions are given by de Morgan's laws:. See also Boolean algebra; sample space.
Subjects: Probability and Statistics.