Proposition (Probability Rules)

Let $A_1,...,A_n$ be events. 1. $P(\emptyset)=0$ 2. Finite Additivity: If $A_1,...,A_n$ are disjoint, then: $$P(\bigcup_{i=1}^n A_i) = \sum_{i=1}^n P(A_i)$$ 3. $P(A^c_1)=1-P(A_1)$ 4. If $A_1\subset A_2$, then $P(A_1)\leq P(A_2)$