X-Git-Url: http://gitweb.michael.orlitzky.com/?p=mjotex.git;a=blobdiff_plain;f=mjo-arrow.tex;h=8b44ded1753eb175124ed71fa73ad4e5ec9b35e5;hp=75b70c9d8b3670d94fb5ed5ca953d20b2464a008;hb=987368c596bfe23dbcbaf5260a0d7011c9d3fc1e;hpb=6e017b796214315c5df54cf94b2504e0cff2a711

diff --git a/mjo-arrow.tex b/mjo-arrow.tex
index 75b70c9..8b44ded 100644
--- a/mjo-arrow.tex
+++ b/mjo-arrow.tex
@@ -2,6 +2,8 @@
 % Things dealing with arrows in a category. Or functions, basically.
 %
 
+\input{mjo-common}
+
 % The identity operator/arrow on its argument.
 \newcommand*{\identity}[1]{ \operatorname{id}_{{#1}} }
 
@@ -11,3 +13,6 @@
 
 % 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} }