Set Notations and Elements

A set is always composed of precisely defined elements. These elements are written between curly braces and separated by commas.

In the example above, set A contains four elements: the numbers 2, 4, 6, and 8.

∈ and ∉ Notations

• The ∈ symbol indicates that an element belongs to the set. For example: 4 ∈ A.
• The ∉ symbol indicates that an element is not part of the set. For example: 5 ∉ A.

Ways to Define Sets

• By enumeration: A = {1,2,3,4,5}.
• By property: B = {x | x is an even number and x < 10}.

Examples with Everyday Elements

• The class students: {Anna, Béla, Csilla, Dénes}.
• The colors of the rainbow: {red, orange, yellow, green, blue, indigo, violet}.
• The Hungarian vowels: {a, á, e, é, i, í, o, ó, ö, ő, u, ú, ü, ű}.

Practice Exercise