Math & Science ⇒ Label for Theorem in custom Class

[dejan85]

I need to put \label in the {theorem} environment like this:

Code: Select all

\documentclass{article}
\usepackage{amsthm}

\newtheorem{theorem}{Theorem}

\begin{document}
\begin{theorem}
This is Theorem.
\label{label}
\end{theorem}
\end{document}

I am writing to IJPRAI journal and I must use their style. When I change the style

Code: Select all

\documentclass{ws-ijprai}

\begin{document}
\begin{theorem}
This is Theorem.
%\label{label}
\end{theorem}
\end{document}

I got error if I uncomment the label command

Code: Select all

! Undefined control sequence.
<write> \newlabel{label}{{\p@Theorem 
                                     \theTheorem }{\thepage }}

I read their instruction file and they don't write how to label theorem.
They probably have predefined theorem environment which does not allow putting label inside theorem. Does anybody know how to solve the problem? I attached their file style.

[cgnieder]

There is a bug in the class in the way it defines \newtheorem. I found a possible workaround which is not very robust. A better way would be to actually fix the definition.

Use with care:

Code: Select all

\documentclass{ws-ijprai}
\usepackage{etoolbox}

\makeatletter
\patchcmd\@opargbegintheorem
  {\@currentlabel{\csname p@#1\endcsname\csname the#1\endcsname}}
  {\lowercase{\@currentlabel{\csname p@#1\endcsname\csname the#1\endcsname}}}{}{F}
\makeatother

\begin{document}

\begin{theorem}
This is Theorem.
\label{label}
\end{theorem}

\ref{label}

\end{document}

Regards