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gitweb.michael.orlitzky.com - mjotex.git/blob - mjo-proof_by_cases.tex
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.
11 \ifx\havemjoproofbycases\undefined
12 \def\havemjoproofbycases{1}
15 % Used below to define pcases. The ``loadonly'' parameter prevents
16 % a very bad interaction with the beamer document class.
17 \usepackage[loadonly
]{enumitem
}
19 % Needed to perform division in the definition of \singleblskip.
22 % A \baselineskip without the \baselinestretch scaling factor. Even
23 % though \baselinestretch defaults to 1.0, it doesn't really have that
24 % value. Thus to avoid division by zero, we need to do the ``is this
25 % thing empty?'' hack.
27 % If we use \baselineskip instead of \singleblskip in our list, things
28 % get real ugly when the text is e.g. double-spaced.
30 \newlength{\singleblskip}
31 \setlength{\singleblskip}{
33 \if\relax\detokenize{\baselinestretch}\relax
40 % Using the enumitem package, we define a new type of list, called
41 % ``pcases'' (proof by cases). Each case has a label with an arabic
42 % numeral (the case number), but also a \thiscase identifier. The
43 % macro \thiscase is defined below by the \case command, and gives the
44 % name or conditions or whatever that distinguish one case from
46 \newlist{pcases
}{enumerate
}{1}
48 label=
\textit{Case~
\arabic*
}:~
\protect\thiscase\textit{.
},
51 listparindent=
\parindent,
53 itemsep=
\singleblskip}
55 % The optional argument here gets stuffed into the \thiscase macro, to
56 % be called by pcases when it creates this list item. The \hfill is a
57 % hack intended to force the proof to start on a new line, rather than
58 % right after the colon. A \newline where the \hfill is does not work,
59 % so we consume the rest of the line instead.
60 \newcommand{\case}[1][]{
62 \item \hfill\par\vspace{\singleblskip}