In
probability theory, the
complement of any
event A is the event [not
A], i.e. the event that
A does not occur. The event
A and its complement [not
A] are
mutually exclusive and
exhaustive. Generally, there is only one event
B such that
A and
B are both mutually exclusive and exhaustive; that event is the complement of
A. The complement of an event
A is usually denoted as
A',
Ac or . Given an event, the event and its complementary event define a
Bernoulli trial: did the event occur or not?