For example. A This collection is such an event {I am a woman}, and the probability of this event is 0, because I am a man. A is not empty at this time. There is an event in it, that is, "I am a woman."
Extended data
Let A and B be mutually incompatible events (AB=φ), then:
P(A∪B)=P(A)+P(B)
Inference 1: If A 1, A2, …, An are incompatible with each other, then: P (A1+A2+...+An) = P (A1)+P (A2)+…+P (An).
Inference 2: Let A 1, A2, ..., A form a complete event group, then: P (A1+A2+...+An) =1.
Inference 3:?
Contrary to event a.
Inference 4: if b contains a, then P (B-A) = P (B)-P (A).
Inference 5 (generalized addition formula):
For any two events a and b, there is P (A ∪ B) = P (A)+P (B)-P (AB).