Sets

A set is an unordered collection of objects. We can construct in different ways, such as by a list: or by a property: If is an element of a set we write .

In this course we use the notation .

If are sets such that every element of is in , we call a subset of and write . If also , we call a proper subset of and write .

The expression in this course refers to .

For any two sets the intersection of and is and the union of and is

For any two sets We define the Cartesian product