# labels for itemize in proposition

I have a Proposition which consists of an itemize with three claims, i.e.

\begin{prop}
\begin{itemize}
\item[(i)] ...
\item[(ii)] ...
\item[(iii)] ...
\end{itemize}
\end{prop}


I wish to insert labels and references in such a way to get things like

"...due to Proposition 4.1 (ii)..." or similar. How can I do? Should I use enumerate instead of itemize? Thanks.

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You could use the enumitem package, with which you could write:

\begin{Proposition}
It is long known that
\begin{enumerate}[label=\roman(*)]
\item all numbers are interesting, but
\item some numbers are more interesting than others.
\end{enumerate}
\end{Proposition}

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Good answer. However, you shouldn't reference my answer implicitly using "Or, ...". The order of answers with the same number of votes is random and having your one on top reads a little funny when it starts like that. ;-) –  Martin Scharrer Feb 24 '11 at 0:37
@Martin: I've fixed that. @Yossi: It would also be nice to see how references work with your solution. –  Hendrik Vogt Feb 24 '11 at 13:17
label=\roman(*) did not work for me and threw an error. However, label=(\roman*) works just fine. Maybe this is due to a newer version. –  user1658887 Aug 25 '13 at 20:58

Yes, an enumerate environment should be used here. After all it is a form of enumeration. You can change the item label by redefining \labelenumi (for first level, deeper levels are \labelenumii, \labelenumiii and \labelenumiv). You can then \label every \item you want to reference. The format of the reference text is given by \theenumi (\theenumii, ...).

I'm not sure if the prop environment you mention comes from a package, so I defined it here for the sake of completeness:

\documentclass{report}

\newcounter{prop}[chapter]
\renewcommand*{\theprop}{\thechapter.\arabic{prop}}

\newenvironment{prop}{%
\refstepcounter{prop}%
\paragraph{Proposition~\theprop}%
\renewcommand*{\theenumi}{\theprop\,(\roman{enumi})}%
\renewcommand*{\labelenumi}{(\roman{enumi})}%
\enumerate
}{%
\endenumerate
}

\begin{document}

\chapter{Test}

\begin{prop}
\item ...
\item\label{name} ...
\item ...
\end{prop}

...due to Proposition \ref{name} ...

\end{document}


Result:

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Try this:

\begin{Proposition}
It is long known that
\begin{enumerate}[label=\roman(*)]
\item all numbers are interesting, but
\item\label{itm:name} some numbers are more interesting than others.
\end{enumerate}
\label{prop:name}
\end{Proposition}


and then the cross-reference is:

  \ref{prop:name}.\ref{itm:name}.

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Welcome to TeX.SX. Seems like this is duplicating an answer already give below. –  Harish Kumar Jan 17 '13 at 2:27