Set notation

• How Do You List the Elements of a Set?
  A set’s elements can be listed only when its definition is known. Learn how to expand set-builder notation and write finite or infinite sets.
• What Does It Mean for a Set Not to Contain the Empty Set?
  A set that does not contain the empty set satisfies ∅ ∉ A; this differs from being nonempty and from the fact that ∅ is a subset of every set.