Notes by Lex Toumbourou

When a Set has too many elements to list, we can use the Set-Builder Notation, which looks like this:

\begin{align} A = \{X | x \in \text{ days of the weekend }\} \\ = \{ \text{Sunday, Saturday} \} \end{align}

The $|$ operator here means "such that", i.e., $x$ for all $x$ such that $x$ is a day of the weekend.