Set is a collection of things, called elements.

Notation defining a set:

Capital letters are used for set names, elements are separated with comma and ellipsis (…) is used:

  •  as a shortcut for listing many elements, when in the middle for finite sets
  • to indicate a set goes on forever, when at the end for infinite sets

Notation for representing:

  • An element belongs to a set:
  • An element does not belong to a set: