7

I have an split equation.

\documentclass{article}

\usepackage{mathtools}

\begin{document}

\begin{equation*}
\label{eq:elig}
\begin{split}
\Omega_{v} := \{(a,\sigma)|a \in A &\wedge b \in B \wedge x(a,b)=v\\ &\wedge (\forall \sigma' \in B)[x(a,\sigma')! \neq v \rightarrow ( \sigma' \in \Sigma_{\text{hib}} \vee b \in \Sigma_{\text{for}})]\}
\end{split}
\end{equation*}

\end{document} 

I need to add an overbrace to the upper piece and ans underbrace to the lower one, but the following does not work.

\documentclass{article}

\usepackage{mathtools}

\begin{document}

\begin{equation*}
\label{eq:elig}
\begin{split}
\Omega_{v} := \{(a,\sigma)|\overbrace{a \in A &\wedge b \in B \wedge x(a,b)=v}^{\alpha}\\ &\wedge \underbrace{(\forall \sigma' \in B)[x(a,\sigma')! \neq v \rightarrow ( \sigma' \in \Sigma_{\text{hib}} \vee b \in \Sigma_{\text{for}})]}_{\beta}\}
\end{split}
\end{equation*}

\end{document}

I just checked some other questions like the one below, but they are about different situations like tables.

Overbrace in amsmath align environment

Here is what I really need:

enter image description here

  • What makes you think you can use & in the argument of \overbrace? Can you show an approximate representation of the desired output? – egreg Dec 12 '17 at 18:23
  • @egreg: please have a look at the added image. – A.Loc Dec 12 '17 at 18:33
7

I don't think you need to align the two \wedge symbols: a multline is better.

\documentclass{article}

\usepackage{mathtools}

\begin{document}

\begin{multline*}
\label{eq:elig}
\Omega_{v} := \{(a,\sigma)\mid
  \overbrace{a \in A \wedge b \in B \wedge x(a,b)=v}^{\alpha}\\
  \wedge \underbrace{(\forall \sigma' \in B)[x(a,\sigma')!
     \neq v \rightarrow ( \sigma' \in \Sigma_{\mathrm{hib}}
     \vee b \in \Sigma_{\mathrm{for}})]}_{\beta}
\,\}
\end{multline*}

\end{document}

enter image description here

  • @Thanks for the help! Just for the sake of curiosity, isn't it possible to handle the issue for the case of split without switching to multline? – A.Loc Dec 12 '17 at 18:52
  • 1
    What if the wedge alignment is a requirement? Of course, I know that one can shift the lower part by hspace{}, but I thought you may have a better idea for that. – Roboticist Dec 12 '17 at 18:57
  • 3
    @Roboticist: You can use \phantom. – Werner Dec 12 '17 at 19:06
9

You can insert \phantom content to align \wedge:

enter image description here

\documentclass{article}

\usepackage{amsmath}

\begin{document}

\begin{align*}
  & \Omega_v := \bigl\{ (a, \sigma) \mid
    \overbrace{a \in A \wedge b \in B \wedge x(a, b) = v}^{\alpha} \\
  & \phantom{\Omega_v := \bigl\{ (a, \sigma) \mid a \in A} % for alignment with \wedge
    \wedge \underbrace{(\forall \sigma' \in B) [x(a, \sigma')!
      \neq v \rightarrow ( \sigma' \in \Sigma_{\mathrm{hib}}
      \vee b \in \Sigma_{\mathrm{for}})]}_{\beta}
  \bigr\}
\end{align*}

\end{document}
3

In case you have reasons to keep the alignment symbols (like here), there is an alternative based on tikz:

\documentclass{article}
\usepackage{mathtools}
\usepackage{tikz}
\usetikzlibrary{matrix,decorations.pathreplacing,calc}
% from https://tex.stackexchange.com/questions/339526/confusion-over-use-of-tikzmark
\newcommand{\tikzmark}[1]{\tikz[overlay,remember picture] \node (#1) {};}
\begin{document}

\begin{equation*}
\label{eq:elig}
\begin{split}
\Omega_{v} := \{(a,\sigma)|\tikzmark{a}a \in A &\wedge b \in B \wedge
x(a,b)=v\tikzmark{v}\\ 
&\wedge \tikzmark{lb}(\forall \sigma' \in B)[x(a,\sigma')! \neq v \rightarrow
( \sigma' \in \Sigma_{\text{hib}} \vee b \in \Sigma_{\text{for}})\tikzmark{rb}]\}
\end{split}
\end{equation*}
\tikz[remember picture, overlay,decoration={brace}]{%
\draw[decorate,transform canvas={xshift=0em,yshift=0.75em},thick] (a.north) -- (v.north) node[above=3pt,midway] {$\alpha$};
\draw[decorate,transform canvas={xshift=0em,yshift=-0.5em},thick] (rb.south) -- (lb.south) node[below=3pt,midway] {$\beta$};}
\end{document}

enter image description here

Here you can control the distance of the brace, its thickness etc. Whether this is an advantage or disadvantage is a matter of taste.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.