# Numbering for a theorem and enumerated list within that theorem

I have the following amsthm environment defined

\newtheorem{cslist}{Comparative Static Hypothesis}


In instances of cslist, I would like to have an enumerated list like this.

 \begin{cslist}{Response A}
\begin{enumerate}
\item \label{item:pps1} Pred 1
\item \label{item:pps2} Pred 2
\end{enumerate}
\end{cslist}


Currently, this renders as Comparative Static Hypothesis 1, with points 1 and 2. I want to have the hypothesis numbering be CS#. Thus, my hypothesis would be Comparative Static Hypothesis CS1. Then, the points in the enumerate should be CS1.i and CS1.ii.

How do I go about making this happen?

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You could redefine the numbering of your "Comparative Static Hypothesis" to show CS# using

\renewcommand{\thecslist}{CS\arabic{cslist}}


and then use the enumitem package to format the labels printed within your cslist environment using label=\thecslist.\roman* (here \roman* will print lower case Roman numerals). Since the labels are now "bigger" than the regular ones, adding leftmargin=* will allow for proper alignment with the left margin.

Here is a minimal example:

\documentclass{article}
\usepackage{enumitem}% http://ctan.org/pkg/enumitem
\usepackage{amsthm}% http://ctan.org/pkg/amsthm
\newtheorem{cslist}{Comparative Static Hypothesis}
\renewcommand{\thecslist}{CS\arabic{cslist}}%
\begin{document}

\begin{cslist}{Response A}
\begin{enumerate}[label=\thecslist.\roman*,leftmargin=*]
\item \label{item:pps1} Pred 1
\item \label{item:pps2} Pred 2
\end{enumerate}
\end{cslist}

\end{document}​


If this usage is more prevalent, perhaps defining a new list cslistenum (say) with default options label=\thecslist.\roman*,leftmargin=* could be defined using

\newlist{cslistenum}{enumerate}
\setlist{cslistenum}[label=\thecslist.\roman*,leftmargin=*]


Alternatively, the etoolbox package could also be used to reformat enumerate with these options by default using \AtBeginEnvironment, thereby automating the reformatting. It all depends on the usage.

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Thank you. This helps a lot. So, for any theorem environment xyz, then \thexyz is the command that makes the name, and xyz is a counter, and \arabic formats the counter? That's really cool. Thank you! –  stevejb Feb 7 '12 at 5:04
@stevejb: Yes, for a theorem environment xyz, an accompanying counter xyz is defined. \thexyz prints the counter in whichever way it has been set to print: \arabic{xyz} prints "regular" numerals; \alph{xyz} [\Alph{xyz}] prints lower [upper] case letters, and \roman{xyz} [\Roman{xyz}] prints lower [upper] case Roman numbers. \value{xyz} is (La)TeX's internal representation of the counter xyz, and could be completely different from what \thexyz prints. –  Werner Feb 7 '12 at 5:14
Thank you @Werner. I really appreciate the information. –  stevejb Feb 7 '12 at 5:42