% The composition of two arrows/functions. For example, the
% composition of g with f is \compose{g}{f}\of{x} === g\of{f\of{x}}.
-\newcommand*{\compose}[2]{ {#1} \circ {#2} }
+\newcommand*{\compose}[2]{ {#1}\circ{#2} }
+
+% The inverse of an arrow, function, or whatever.
+\newcommand*{\inverse}[1]{ #1^{-1} }