Sets
Sets: A set is a collection of objects, called elements of the set. A set can be represented by listing its elements between braces:
A = {1, 2, 3, 4, 5}. The symbol ∈ is used to express that an element is (or belongs to) a set, for instance 3 ∈ A. Its negation is represented by ∉ , e.g. 7 ∉ A. If the set is finite, its number of elements is represented |A|, e.g. if A = {1, 2, 3, 4, 5} then |A| = 5.
Find out more about sets by reading the explanation below.
Practice: Answer the following exercises to learn to define sets and find the intersection, union, complement and difference of sets.