1. For any event A, 0 ≤ P(A) ≤ 1.
2. P(impossible event) = 0.
Also written P(empty set) = 0 or P(
) = 0.
3. P(sure event) = 1.
Also written P(S) = 1, where S is the sample space.
4. P(not A) = 1 – P(A).
Also written P(complement of A) = 1 – P(A) or P(AC) = 1 – P(A) or
.