Given an event in a Sample Space which is either finite with elements or countably infinite with
elements, then we can write

and a quantity , called the Probability of event , is defined such that

- 1. .
- 2. .
- 3. Additivity: , where and are mutually exclusive.
- 4. Countable additivity: for , 2, ..., where , , ...are mutually exclusive (i.e., ).

© 1996-9

1999-05-26