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Discrete Mathematical Structures

Subsection 0.1.1 Sets

We give basic terminology and notation for sets. We cover sets in more detail in Section 2.1.
A set is an unordered collection of objects, called elements or members of the set. We write \(b \in A\) when \(b\) is an element of the set \(A\text{.}\) We read \(b \in A\) as “\(b\) is an element of \(A\)” or “\(b\) is in \(A\)”.
Sets can be specified in roster form by listing the elements explicitly between braces. For example, \(\set{1, 2, 7}\) is the set containing \(1\text{,}\) \(2\text{,}\) and \(7\text{.}\)
To indicate that the list of elements continues in a pattern that can be deduced from the preceding list of elements we use ellipsis (\(\ldots\)). For example, we have
\begin{equation*} \set{1, 2, 3,\dots, 10}=\set{1,2,3,4,5,6,7,8,9,10}\text{.} \end{equation*}