等式中的换行符

Question

我如何让等式中的线断开，就像下面的例子中 starName=name 和birthdate=1960 之间的线一样。

\begin{document}
$\Pi_{movieTitle} \sigma_{starName = name \wedge birthDate = 1960}(StarsIn \times MovieStar)$
\end{document}

Answer 1

\documentclass{article}
\usepackage{stackengine}
\stackMath
\begin{document}
$\pi_{\mathtt{movieTitle}}\sigma 
  \stackunder{\scriptstyle\mathtt{starName=name}}
    {\scriptstyle\wedge\mathtt{birthdate=1960}}
  (\mathtt{StarsIn} \times \mathtt{MovieStar}).$
\end{document}

Answer 2

下面是使用\substack该amsmath包的宏的解决方案：

\documentclass{article}
\usepackage{amsmath} % for \substack macro
\newcommand{\V}[1]{\texttt{#1}} % place argument in monospaced font
\begin{document}
$\Pi_{\V{MovieTitle}} \ 
\sigma_{\substack{\V{StarName} = \V{name}\\ \wedge\V{BirthDate} = 1960}}\ (\V{StarsIn}\times \V{MovieStar})$
\end{document}