Relationships Between Events

Two events A and B chosen from the same sample space are called mutually exclusive or disjoint if there is no common outcome for A and B. This property is denoted by (A∩B) = ∅. That is, the intersection of the sets A and B is empty.

For example, the events {1, 3} and {2, 4, 6} are mutually exclusive events in the rolling a die. This concept can be illustrated by the figure below, in which the rectangle considered as the sample space of an experiment, and the circles A and B display the two disjoint events: