Replace all uses of \providecommand with \newcommand.

[mjotex.git] / mjo-arrow.tex

diff --git a/mjo-arrow.tex b/mjo-arrow.tex
index 75b70c9d8b3670d94fb5ed5ca953d20b2464a008..4dd5f88bc6053dd224dd3c7b138ff757c78fe301 100644 (file)
--- a/mjo-arrow.tex
+++ b/mjo-arrow.tex
@@ -1,6 +1,11 @@
 %
 % Things dealing with arrows in a category. Or functions, basically.
 %
+\ifx\havemjoarrow\undefined
+\def\havemjoarrow{1}
+
+
+\input{mjo-common}
 
 % The identity operator/arrow on its argument.
 \newcommand*{\identity}[1]{ \operatorname{id}_{{#1}} }
@@ -11,3 +16,9 @@
 
 % The inverse of an arrow, function, or whatever.
 \newcommand*{\inverse}[1]{ #1^{-1} }
+
+% The preimage of the second argument (a set) under the first (a function).
+\newcommand*{\preimage}[2]{ #1^{-1}\of{#2} }
+
+
+\fi