# Enumerating inside a proposition and inside a proof

I have one problem with enumerating. The symbols for items look differently when the enumerating is done ''inside'' propositions from the enumerating done ''inside'' a proof.

The code

\documentclass[11pt,a5paperfootinclude=true,headinclude=true]{scrbook} % KOMA-Script book
\usepackage[T1]{fontenc}
\usepackage{lipsum}
\usepackage[bitstream-charter]{mathdesign}
%\usepackage[osf]{libertine}
\titleformat{\section}
{\normalfont\bfseries}{\thesection}{1em}{}

\usepackage{amsthm}
\usepackage{amsmath}
\usepackage{multicol}
\usepackage{IEEEtrantools}

\usepackage{anysize}
\marginsize{0.1\paperwidth}{0.1\paperheight}{2cm}{2cm}
\newcommand{\bigslant}[2]{{\raisebox{.2em}{$#1$}\left/\raisebox{-.2em}{$#2$}\right.}}

\usepackage{enumerate}

\begin{document}

\theoremstyle{plain}
\newtheorem{thm}{Theorem}[chapter] % reset theorem numbering for each chapter

\theoremstyle{definition}
\newtheorem{defn}[thm]{Definition} % definition numbers are dependent on theorem numbers
\newtheorem{exmp}[thm]{Example}

\theoremstyle{corollary}
\newtheorem{cor}[thm]{Corollary}

\theoremstyle{lemma}
\newtheorem{lem}[thm]{Lemma}

\theoremstyle{proposition}
\newtheorem{prop}[thm]{Proposition}
\newcommand{\ndiv}{\hspace{-4pt}\not|\hspace{2pt}}

\begin{prop}
\begin{enumerate}[(a)] % (a), (b), (c), ...
\item
\item
\end{enumerate}
\end{prop}

\begin{proof}
\begin{enumerate}[(a)] % (a), (b), (c), ...
\item
\item
\end{enumerate}
\end{proof}

\end{document}


and the result

Is there any remedy for this, so they look identical or is it impossible? Can we also make a reference to the enumerated item?

Thank you

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I'd use the enumitem package that's much more flexible than enumerate and define a new environment for that kind of enumerations in theorems and proofs.

\documentclass[11pt,a5paper,footinclude=true,headinclude=true]{scrbook} % KOMA-Script book
\usepackage[T1]{fontenc}
\usepackage[bitstream-charter]{mathdesign}

\usepackage{lipsum}
\usepackage{amsmath}
\usepackage{amsthm}

\usepackage{enumitem}

\theoremstyle{plain}
\newtheorem{thm}{Theorem}[chapter] % reset theorem numbering for each chapter
\newtheorem{cor}[thm]{Corollary}
\newtheorem{lem}[thm]{Lemma}
\newtheorem{prop}[thm]{Proposition}

\theoremstyle{definition}
\newtheorem{defn}[thm]{Definition} % definition numbers are dependent on theorem numbers
\newtheorem{exmp}[thm]{Example}

\newenvironment{roster}
{\begin{enumerate}[font=\upshape,label=(\alph*)]}
{\end{enumerate}}

\begin{document}

\begin{prop}
\begin{roster}
\item Something
\item Something else
\end{roster}
\end{prop}

\begin{proof}
\begin{roster}
\item Easy
\item The same\qedhere
\end{roster}
\end{proof}

\end{document}


Note that the theorem declarations should go before \begin{document} and that you're using inexistent styles. I removed the inessential bits.

For ending a proof within an enumeration, use \qedhere, so that the tombstone will be placed on the last line.

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Thank you. Very good tip. – user124471 Mar 14 '14 at 12:34
@ egreg If I want to (a) does not lie in of Proposition. How must I do? – minthao_2011 Mar 14 '14 at 15:39
@minthao_2011 That's a different problem. My opinion is that it should; add \mbox{} before \begin{roster}. – egreg Mar 14 '14 at 15:40

You can set your item labels as [\upshape (a)] instead of [(a)]. Note that \textup{(a)} won't work with the enumarate package and as the placeholder a is hidden in a group {...}.

\documentclass{article}

\usepackage{amsthm,enumerate}

\newtheorem{theorem}{Theorem}[section]

\begin{document}

\begin{theorem}
This has two parts.
\begin{enumerate}[\upshape (a)]
\item First part.
\item Second part.
\end{enumerate}
\end{theorem}

\begin{proof}
Also two parts to the proof.
\begin{enumerate}[\upshape (a)]
\item Proof of first part.
\item Proof of second part.
\end{enumerate}
\end{proof}

\end{document}

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Thank you. They look identical now, which is exactly what I wanted. – user124471 Mar 14 '14 at 11:55

A similar solution with enumitem, but emphasising the fact that cross-referencing the items within a theorem environment works with enumitem, while it did not withenumerate. I also loaded thecleverref package, as it allows not to type the kind of object that is being referenced, but only its label – so that if a theorem becomes in a later version a proposition, you do not have to do a search-and-replace.

        \documentclass[11pt,a5paperfootinclude=true,headinclude=true]{scrbook} % KOMA-Script book
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}

\usepackage{titlesec}
\titleformat{\section} {\normalfont\bfseries}{\thesection}{1em}{}

\usepackage{amsthm}
\usepackage{amsmath}
\usepackage[shortlabels]{enumitem}

\usepackage{cleveref}

\theoremstyle{plain}
\newtheorem{thm}{Theorem}[chapter] % reset theorem numbering for each chapter

\theoremstyle{definition}
\newtheorem{defn}[thm]{Definition} % definition numbers are dependent on theorem numbers \newtheorem{exmp}[thm]{Example}

\newtheorem{cor}[thm]{Corollary}
\newtheorem{lem}[thm]{Lemma}
\newtheorem{prop}[thm]{Proposition}

\begin{document}

\begin{prop}\label{pr1}
\begin{enumerate}[\upshape(a)] % (a), (b), (c), ...
\item  \label{item1} Once upon a time…
\item So what?
\end{enumerate}
\end{prop}

\begin{proof} \begin{enumerate}[(a)] % (a), (b), (c), ...
\item According to \cref{pr1}\ref{item1}

\item What else? \qedhere

\end{enumerate}
\end{proof}
\end{document}
`

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