Pairwise independence

A property of a collection of events in which every pair of events is mutually independent, so P(Aᵢ ∩ Aⱼ) = P(Aᵢ)P(Aⱼ) for all pairs i ≠ j. Pairwise independence is weaker than mutual independence; a set of pairwise-independent events can still exhibit higher-order dependence among triples or larger subsets.