Two [[Event|Events]] or [[Proposition|Propositions]] are [[Mutually Exclusivity|Mutually Exclusive]] (or [[Mutually Exclusivity|Disjoint]]) if they cannot occur simutaneously. Two [[Proposition|Propositions]] $\phi, \psi$ are mutually exclusive if $\neg(\phi \wedge \psi)$ is a [[Tautology]]. The [[Event|Events]] $E_{0},E_{1},E_{2},\dots,E_{n}$ are mutually exclusive [[Bijective|if and only if]] for any $i,j \in [0,n]\, E_{i}\neq E_{j}$, $E_{i} \cap E_{j} =\emptyset$, that is to say that there is no [[Intersection|Intersection]] between any non-equal [[Event|Events]] $E_{i}, E_{j}$.