# Need help with a cases structure inside an enumerated list

I need to type an enumerated list (for a math document) that contains several lines for which I need to have said lines have a curly brace at the end with a text description for them. The best I can do for know is point to the following link: https://www.mediafire.com/#3eshxd2tsdacf page number 5, and Theorem 1.1.1. I need what I am doing to essentially look like that enumerated list. Can anyone help please?

Here is a screenshot:

• Jul 28, 2013 at 12:24

I would set this in an array with manual numbering:

\documentclass{article}
\usepackage{amsmath,array}% http://ctan.org/pkg/{amsmath,array}
\newcommand{\twolinebrace}{\rlap{$\smash{\raisebox{.5\height}{\bigg\}}}$}}
\newlength{\LHS}\newlength{\RHS}
\settowidth{\LHS}{$P \OR (Q \OR R)$}\settowidth{\RHS}{$(P \AND Q) \OR (P \AND R)$}
\newcolumntype{M}{>{$}p{\LHS}<{$}}
\newcolumntype{N}{>{$}p{\RHS}<{$}}
\begin{document}
$\renewcommand{\arraystretch}{1.1} \begin{array}{@{}l@{\quad}l@{}} \begin{array}{>{\bfseries}p{2em}@{\quad}M@{\quad\text{and}\quad}N} (a) & P & \NOT (\NOT P) \end{array} & \text{Double Negation Law} \\ \left.\kern-\nulldelimiterspace\begin{array}{>{\bfseries}p{2em}@{\quad}M@{\quad\text{and}\quad}N} (b) & P \OR Q & Q \OR P \\ (c) & P \AND Q & Q \AND P \end{array}\right\} & {\text{Commutative Laws}} \\ \left.\kern-\nulldelimiterspace\begin{array}{>{\bfseries}p{2em}@{\quad}M@{\quad\text{and}\quad}N} (d) & P \OR (Q \OR R) & (P \OR Q) \OR R \\ (e) & P \AND (Q \AND R) & (P \AND Q) \AND R \end{array}\right\} & {\text{Associative Laws}} \\ \left.\kern-\nulldelimiterspace\begin{array}{>{\bfseries}p{2em}@{\quad}M@{\quad\text{and}\quad}N} (f) & P \AND (Q \OR R) & (P \AND Q) \OR (P \AND R) \\ (g) & P \OR (Q \AND R) & (P \OR Q) \AND (P \OR R) \end{array}\right\} & {\text{Distributive Laws}} \\ \left.\kern-\nulldelimiterspace\begin{array}{>{\bfseries}p{2em}@{\quad}M@{\quad\text{and}\quad}N} (h) & \NOT (P \AND Q) & {\NOT P} \OR {\NOT Q} \\ (i) & \NOT (P \OR Q) & {\NOT P} \AND {\NOT Q} \end{array}\right\} & {\text{DeMorgan's\textsuperscript{*} Laws}} \end{array}$
\end{document}


Column type M is defined to fit the left-hand side of every law, while N is for the right-hand side. Their lengths are determined before the to fit exactly the contents of the column.

I assume the first column numbering could be automated, but it doesn't warrant that here in my opinion. One caveat with this approach is that the block is not breakable across the page boundary. It could be made that way by using amsmath's breakable alignment, keeping pairs together in an array still.