## 2.2 Outline

- Fundamental operations
- intersection; “and”
- union; “or”

- Cardinality of intersections and union
- Venn diagram for union
- Formula

## 2.2 Essential Ideas

**Operations with Sets**

Remember the basic operations:

**Complement**

The complement of a set *S* is consists of everything that is not in *S*.

**Union**

The union of two sets is everything that is in either set; that is, anything colored

(blue, yellow, or green).

**Intersection**

The intersection of two sets is everything that is in both sets; that is, anything

colored both blue and yellow, namely green.

**Cardinality of Intersections and Unions**

The **cardinality of an intersection** is the number of elements in the intersection.

The **cardinality of a union** is the sum of the cardinalities of the given sets

less the number of elements in the intersection.