Strange error related to theorem name (XeTeX)

Question

Trying to have a theorem with [name=Dominio e codominio dell'operatore $D^{\vct{q}}$,label=thm:oss:DomCodomDq] gives the following error:

The error on the TeXShop console

The error is given by the following MWE:

\documentclass[a4paper]{report}  
\usepackage{amsmath,amssymb,thmtools}  
\newtheorem{oss}{Osservazione}  
\begin{document}  
\begin{oss}[name=Dominio e codominio dell'operatore $D^{\overrightarrow{q}}$,label=thm:oss:DomCodomDq]  
\end{oss}  
\end{document}

where \vct has been replaced by its primitive name \overrightarrow. The error is apparently related to \vct, as removing that removes the error. What does that mean and how do I solve it?

Without knowing how you defined \vct, how can we tell something sensible? — egreg, Dec 30 '13 at 11:43
As a quick work around use ...$D^{\vec{q}}$... to avoid the error. — Thruston, Dec 30 '13 at 11:48
Fragile command in a moving argument: \protect\overrightarrow when used in name= fixes the issue. — egreg, Dec 30 '13 at 11:49

score 1 · Accepted Answer · answered Dec 30 '13 at 11:53

1

define a dummy:

\documentclass[a4paper]{report}  
\usepackage{amsmath,amssymb,thmtools}  
\newtheorem{oss}{Osservazione}  
\begin{document}  
\def\dummy{$D^{\overrightarrow{q}}$}
\begin{oss}[name=Dominio e codominio dell'operatore \protect\dummy,label=thm:oss:DomCodomDq]  
\end{oss}  
\end{document}

or use:

$D^{\protect\overrightarrow{q}}

answered Dec 30 '13 at 11:53

The \dummy thing, I think, goes against the What You See Is What You Mean principle, so I prefer the direct thing. In any case @egreg, what exactly does this \protect command do? – MickG Dec 30 '13 at 12:43
http://tex.stackexchange.com/questions/4736/what-is-the-difference-between-fragile-and-robust-commands – Dec 30 '13 at 12:46

Strange error related to theorem name (XeTeX)

1 Answers1