# Using there exists symbol within inference of the semantic package

I am using the semantic package to write inference rules. I need to put a there exists symbol which is standard to LaTeX using $\exists$. However, when used within the semantic package's inference command as follows:

\inference[case$_0$]{$\exists$ I}{test}


several errors are encountered :

(./semantics.aux) (/usr/share/texmf-texlive/tex/latex/ucs/ucsencs.def)
! Missing $inserted. &lt;inserted text&gt;$
l.42 \inference[case$_0$]{$\exists$ I}
{test}
! Extra }, or forgotten $. \@processPremiseLine ...ce \end \hskip \@@pSpace } \fi \fi \def \sem@tmp {#2}... l.42 \inference[case$_0$]{$\exists$I} {test} ! Missing$ inserted.
&lt;inserted text&gt;
$l.42 \inference[case$_0$]{$\exists$I} {test} ! Missing } inserted. &lt;inserted text&gt; } l.42 \inference[case$_0$]{$\exists$I} {test} [1] (./semantics.aux) )  Can anyone suggest what I can do please? - ## 2 Answers You can "box" the item using \ensuremath: \documentclass{article} \usepackage{semantic}% http://ctan.org/pkg/semantic \begin{document} \inference[case$_0$]{\ensuremath{\exists~I}}{test} \end{document}  Note the forced spacing as a result of the tie ~. This may just be your preference, which I've stuck to. - thank you .. thats what I needed! – aseychell Dec 7 '11 at 8:03 How does one get a bold version of \exists, or any other version that would have a stronger look? – Maesumi Aug 25 at 20:44 @Maesumi: See How can I get bold math symbols? – Werner Aug 25 at 20:45 The mandatory arguments seem to be in mathmode by definition, so you do not need to enter mathmode. Remove the dollar signs and it works fine. \documentclass{article} \usepackage{semantic} \begin{document} \inference[case$_0\$]{\exists I}{test}
\end{document}

-
Damn, I'm too slow ... – Torbjørn T. Dec 7 '11 at 8:05
works nice aswell .. thanks! – aseychell Dec 7 '11 at 8:18