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2 % A proof-by-cases environment. This gives you a nicely-indented list
3 % of cases for use in proofs.
7 % Case 1 (x >= 0): herp.
9 % Case 2 (x < 0): derp.
12 % Used below to define pcases.
15 % Needed to perform division in the definition of \singleblskip.
18 % A \baselineskip without the \baselinestretch scaling factor. Even
19 % though \baselinestretch defaults to 1.0, it doesn't really have that
20 % value. Thus to avoid division by zero, we need to do the ``is this
21 % thing empty?'' hack.
23 % If we use \baselineskip instead of \singleblskip in our list, things
24 % get real ugly when the text is e.g. double-spaced.
26 \newlength{\singleblskip}
27 \setlength{\singleblskip}{
28 \baselineskip /
\real{
29 \if\relax\detokenize{\baselinestretch}\relax
36 % Using the enumitem package, we define a new type of list, called
37 % ``pcases'' (proof by cases). Each case has a label with an arabic
38 % numeral (the case number), but also a \thiscase identifier. The
39 % macro \thiscase is defined below by the \case command, and gives the
40 % name or conditions or whatever that distinguish one case from
42 \newlist{pcases
}{enumerate
}{1}
44 label=
\textbf{Case~
\arabic*
}:~
\protect\thiscase\textbf{.
},
48 listparindent=
\parindent,
50 itemsep=
\singleblskip}
52 % The optional argument here gets stuffed into the \thiscase macro, to
53 % be called by pcases when it creates this list item. The \hfill is a
54 % hack intended to force the proof to start on a new line, rather than
55 % right after the colon. A \newline where the \hfill is does not work,
56 % so we consume the rest of the line instead.
57 \newcommand{\case}[1][]{
59 \item \hfill\par\vspace{\singleblskip}