Set: Definition

We begin our course by looking into the simplest discrete structure: a set.

A set is an unordered collection of various sorts of objects, which we call items or elements. Examples:

• $\{1, 2, 3\}$
• $\{A, C, E, G\}$
• $\{\text{Alice},\,$$\text{Carol},\,$$\text{Eugene},\,$$\text{George}\}$
• $\{$😀$,$ 😁$,$ 😎$,$ 😜$\}$

We write the elements of a set between a pair of curly braces, $\{$ and $\}$. In $\LaTeX$, we write:

• $\{1, 2, 3\}$

• $\{A, C, E, G\}$

• $\{\text{Alice}, \text{Carol}, \text{Eugene}, \text{George}\}$