# Tutorial

### Set Theory

Relational Algebra has evolved from the set theory you may have experienced in school.

A **set** is a collection zero of more elements, where each element is unique.

- S = {A, B} is a set with the elements A and B.
- A ε S A is an element of S
- {A} ⊂ {A,B} is a subset
- {} or Ø is an empty set.

Go to Tutorial 2