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Being new in LaTeX I don't know where to look for the proper resources. I know this is probably documented for easily somewhere out there, but I'm struggling with knowing where to look - any help isappreciated.
How would you reproduce in LaTeX this conditional expression with one curly brace on the left side?
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\[
t(v) =
\begin{cases}
\text{John} & \text{hvis $v$ er variabelen $x$}\\
\text{Paul} & \text{hvis $v$ er variabelen $y$}\\
\text{George} & \text{hvis $v$ er variabelen $z$}\\
\text{Yoko} & \text{ellers}
\end{cases}
\]
\end{document}
Jendrik notes in the comments that the cases* environment, available with mathtools, sets the right-hand alignment automatically as text, rather than math, which is useful in this situation. Thus, the cases* equivalent of the above code would be
\documentclass{article}
\usepackage{mathtools}
\begin{document}
\[
t(v) =
\begin{cases*}
\text{John} & hvis $v$ er variabelen $x$\\
\text{Paul} & hvis $v$ er variabelen $y$\\
\text{George} & hvis $v$ er variabelen $z$\\
\text{Yoko} & ellers
\end{cases*}
\]
\end{document}
Here's an alternative with tabstackengine, allowing the content to be set in text mode directly:
\documentclass{article}
\usepackage{tabstackengine}
\begin{document}
\[
\setstackgap{L}{1.1\normalbaselineskip}% ROW BASELINESKIP
\setstacktabbedgap{1em}% INTER-COLUMN GAP
t(v) = \left\{
\tabbedCenterstack[l]{% LEFT ALIGNED STACK CONTENT
John & hvis $v$ er variabelen $x$\\
Paul & hvis $v$ er variabelen $y$\\
George & hvis $v$ er variabelen $z$\\
Yoko & ellers
}
\right.
\]
\end{document}
mathtools instead of amsmath (which is then loaded internally by mathtools), and then use cases* instead of cases. In this way, one doesn’t need to use\text{} in the second column.
– Jendrik Stelzner
Apr 28 at 22:30
Another solution with just array and bigdelim:
\documentclass{article}
\usepackage{bigdelim, array}
\begin{document}
\begin{center}
\sffamily
\begin{tabular}{l@{\,}l@{\quad}l}
\ldelim\{{4}{*}[$t(v)={}$]
& John & hvis $v$ er variabelen $x$ \\
& Paul & hvis $v$ er variabelen $y$ \\
& George & hvis $v$ er variabelen $z$ \\
& Yoko & ellers
\end{tabular}
\end{center}
\end{document}
Steven has already said enough, but just for completeness and for proving that LaTeX offers always new roads I'll post another solution by means of .., though I think cases environment is the most appropriate for this job.
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\[
t(v) = \left\{\begin{array}{lr}
\text{John} & \text{hvis $v$ er variabelen $x$}\\
\text{Paul} & \text{hvis $v$ er variabelen $y$}\\
\text{George} & \text{hvis $v$ er variabelen $z$}\\
\text{Yoko} & \text{ellers}
\end{array}\right.
\]
\end{document}
This produces
Notice that amsmath package is only needed for text command. A benefit from using array would be that you can control alignment by means of r and l (respectively right aligned, and left aligned) arguments in \begin{array}{lr}, and you can add lines as well as control manually spacing, by writing
\[
t(v) = \left\{\begin{array}{l@{\hspace{3em}}|r}
\text{John} & \text{hvis $v$ er variabelen $x$}\\
\hline
\text{Paul} & \text{hvis $v$ er variabelen $y$}\\
\text{George} & \text{hvis $v$ er variabelen $z$}\\
\text{Yoko} & \text{ellers}
\end{array}\right.
\]
@{\hspace{3em}} can be set to whichever value in em, cm, pt and other measure you like for making custom space between columns, while | can be used for adding vertical lines bewreen the arry columns. Finally adding \hline you can achieve horizontal rules.
Little addendum: \left\{ and \right. fake the case behaviour of cases environment, so that if you prefer you can switch it to othe parenthesis, as [, (, \langle and so on.
