# 2.1.3.2 - Combinations of Events

In situations with two or more categorical variables there are a number of different ways that combinations of events can be described: intersections, unions, complements, and conditional probabilities. Each of these combinations of events is covered in your textbook. However, note that your textbook does not use the symbols that are most commonly used when discussing these combinations of events. The symbols that we will be using are in the table below. In this section, you will also learn about disjoint events and independent events

Combination of Events
Combination Symbol Definition
Intersection $$P(A\cap B)$$ Probability of A and B
Union $$P(A\cup B)$$

Probability of A or B

Note: This includes the possibility of A and B

Complement $$P(A^C)$$ The probability of NOT A
Conditional $$P(A\mid B)$$ The probability of A given B