# How to create a figure with math content

What's wrong with the following figure in the text? First, it says "amsmath: Unable to redefine math accent \vec." and then "Undefined control sequence" but neither is any helpful to me. It uses LLNCS (Lecture Notes for Computer Science), see http://www.springer.com/computer/lncs?SGWID=0-164-6-793341-0

\documentclass{llncs}
\usepackage{amsmath}
\title{Aussagenlogik}
\author{someone}
\institute{somewhere}

\begin{document}

\maketitle

\section{Einleitung}
\paragraph{...}

\section{Definition einer Aussage}
\paragraph{...
}

$$X sei eine Aussage. Dann ist der Wahrheitswert W(X) wie folgt definiert:\\ W(A) = \begin{cases} wahr, \mbox{wenn X zutrifft}\\ falsch, \mbox{wenn X nicht zutrifft} \end{cases} \cite{Sie}$$

\begin{thebibliography}{999}
\bibitem {Sie} Bla Bla
\end{thebibliography}

\end{document}

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The $ is used to being math, but then right after the dollar you use $?? The \[ starts display math. so you don't need the  before the \[ nor one after $. Furthermore you should use \text{} to enclose you text that is within a math mode environment. – Peter Grill Oct 16 '12 at 15:10 – Peter Grill Oct 16 '12 at 15:18 ## 1 Answer You are using the math mode erronously. Inside $...\$ the math contents are typeset as inline math and $..$ is used for standalone display style math which gives a new line automatically without an eq. number. Also \text{...} is used to temporarily stop the math mode such that the contents are typeset in the regular text style. So

\documentclass{llncs}
\usepackage{amsmath}
\title{Aussagenlogik}
\author{someone}
\institute{somewhere}

\begin{document}

\maketitle

\section{Einleitung}
\paragraph{...}

\section{Definition einer Aussage}
\paragraph{...
}

X sei eine Aussage. Dann ist der Wahrheitswert W(X) wie folgt definiert:
$W(A) = \begin{cases} wahr, \text{wenn X zutrifft}\\ falsch, \text{wenn X nicht zutrifft} \end{cases} \cite{Sie}$

\begin{thebibliography}{999}
\bibitem {Sie} Bla Bla
\end{thebibliography}

\end{document}


-
you probably want to use \mathit for "wahr" and "falsch". (the kerning in "falsch" is particularly awful without it.) –  barbara beeton Oct 16 '12 at 15:20