--- /dev/null
+%
+% A proof-by-cases environment. This gives you a nicely-indented list
+% of cases for use in proofs.
+%
+% Example:
+%
+% Case 1 (x >= 0): herp.
+%
+% Case 2 (x < 0): derp.
+%
+
+% Used below to define pcases.
+\usepackage{enumitem}
+
+% Using the enumitem package, we define a new type of list, called
+% ``pcases'' (proof by cases).
+\newlist{pcases}{enumerate}{1}
+\setlist[pcases]{
+ label=\textbf{Case~\arabic*}~(\protect\thiscase)\textbf{:},
+ ref=\arabic*,
+ align=left,
+ leftmargin=\parindent
+}
+\newcommand{\case}[1][]{
+ \def\thiscase{#1}%
+ \item
+}