Let $A$ and $B$ be two arbitrary events, then :
- $P\left ( A\cap B \right )= P\left ( A \right )P\left ( B \right )$
- $P\left ( P\cup B \right )= P\left ( A \right ) + P\left ( B \right )$
- $P\left ( A\cup B \right )\leq P\left ( A \right ) + P\left ( B \right )$
- $P\left ( A/ B \right )=P\left ( A\cap B \right )+P\left ( B \right )$