\[
\newcommand{\tr}{\Rightarrow}
\newcommand{\trs}{\tr^{\!\ast}}
\newcommand{\rlnm}[1]{\mathsf{(#1)}}
\newcommand{\rred}[1]{\xrightarrow{#1}}
\newcommand{\rreds}[1]{\mathrel{\xrightarrow{#1}\!\!^*}}
\newcommand{\cl}{\mathsf{Cl}}
\newcommand{\pow}{\mathcal{P}}
\newcommand{\matches}{\mathrel{\mathsf{matches}}}
\newcommand{\kw}[1]{\mathsf{#1}}
\newcommand{\andop}{\mathrel{\&\!\&}}
\newcommand{\orop}{\parallel}
\newcommand{\ff}{\mathsf{false}}
\newcommand{\tt}{\mathsf{true}}
\newcommand{\abra}[1]{\langle #1 \rangle}
\newcommand{\bnfnt}[1]{\abra{\small \textsf{#1}}}
\newcommand{\llbracket}{[\![}
\newcommand{\rrbracket}{]\!]}
\newcommand{\first}{\mathsf{First}}
\newcommand{\nullable}{\mathsf{Nullable}}
\newcommand{\follow}{\mathsf{Follow}}
\newcommand{\tm}[1]{\mathsf{#1}}
\newcommand{\nt}[1]{\mathit{#1}}
\newcommand{\Coloneqq}{::=}
\newcommand{\abs}[1]{|#1|}
\]
\[\begin{array}{rll}
\nt{Form} &\to& (\ \tm{define}\ \nt{Ident}\ \nt{SExpr}\ ) \\
&\to& (\ \tm{define}\ \nt{Ident}\ \nt{Num}\ ) \\
&\to^*& (\ \tm{define}\ \tm{x}\ \tm{3}\ )\\[8mm]
\nt{Form} &\to& \nt{SExpr} \\
&\to& (\ \nt{Ident}\ \nt{SExpr}^*\ ) \\
&\to& (\ \nt{Ident}\ \nt{SExpr}\ \nt{SExpr}\ \nt{SExpr}\ \nt{SExpr}\ ) \\
&\to& (\ \nt{Ident}\ \nt{Ident}\ \nt{Ident}\ \nt{Ident}\ \nt{Num}\ ) \\
&\to^*& (\ \tm{def}\ \tm{i}\ \tm{ne}\ \tm{x}\ \tm{3}\ )
\end{array}\]