null event, disjoint

Sometimes $A$ and $B$ have no outcomes in common, so that the intersection of $A$ and $B$ contains no outcomes.

null

Let $\varnothing$ denote the null event (the event consisting of no outcomes whatsoever).

disjoint

When $A\cap B=\varnothing ,A$ and $B$ are said to be mutually exclusive or disjoint events.

• EX 2.10 automobile dealer