Let be any set. The on , denoted , is the set of all permutations of . We denote by the symmetric group on .
%%%%%
% DEPENDENCIES
% RequiredMacros: \newcommand{\textdef}[1]{\textit{#1}} \DeclareMathOperator{\sym}{Sym}
%%%%%
\begin{definition}
Let $X$ be any set. The \textdef{symmetric group} on $X$, denoted $\sym(X)$, is the set of all permutations of $X$. We denote by $S_n$ the symmetric group on $X = \{1,2,\ldots, n\}$.
\end{definition}