X-Git-Url: http://gitweb.michael.orlitzky.com/?p=mjotex.git;a=blobdiff_plain;f=mjo-arrow.tex;h=9bf9dc5555515e45f2a98b25d5c89310375d3b03;hp=8b44ded1753eb175124ed71fa73ad4e5ec9b35e5;hb=f9205a3b883c08499edfdd3f9d1a6170a6fc6755;hpb=987368c596bfe23dbcbaf5260a0d7011c9d3fc1e

diff --git a/mjo-arrow.tex b/mjo-arrow.tex
index 8b44ded..9bf9dc5 100644
--- a/mjo-arrow.tex
+++ b/mjo-arrow.tex
@@ -1,8 +1,27 @@
 %
 % Things dealing with arrows in a category. Or functions, basically.
 %
+\ifx\havemjoarrow\undefined
+\def\havemjoarrow{1}
 
-\input{mjo-common}
+
+\input{mjo-common} % for \of, at least.
+
+\ifx\operatorname\undefined
+  \usepackage{amsopn}
+\fi
+
+
+% The constant function that always returns its argument.
+\newcommand*{\const}[1]{\operatorname{const}_{{#1}}}
+
+\ifdefined\newglossaryentry
+  \newglossaryentry{const}{
+    name={\ensuremath{\const{a}}},
+    description={the constant function that always returns $a$},
+    sort=c
+  }
+\fi
 
 % The identity operator/arrow on its argument.
 \newcommand*{\identity}[1]{ \operatorname{id}_{{#1}} }
@@ -16,3 +35,6 @@
 
 % The preimage of the second argument (a set) under the first (a function).
 \newcommand*{\preimage}[2]{ #1^{-1}\of{#2} }
+
+
+\fi