mjo-arrow.tex

   1 %
   2 % Things dealing with arrows in a category. Or functions, basically.
   3 %
   4 \ifx\havemjoarrow\undefined
   5 \def\havemjoarrow{1}
   6
   7
   8 \input{mjo-common} % for \of, at least.
   9
  10 \ifx\operatorname\undefined
  11   \usepackage{amsopn}
  12 \fi
  13
  14 % The identity operator/arrow on its argument.
  15 \newcommand*{\identity}[1]{ \operatorname{id}_{{#1}} }
  16
  17 % The composition of two arrows/functions. For example, the
  18 % composition of g with f is \compose{g}{f}\of{x} === g\of{f\of{x}}.
  19 \newcommand*{\compose}[2]{ {#1}\circ{#2} }
  20
  21 % The inverse of an arrow, function, or whatever.
  22 \newcommand*{\inverse}[1]{ #1^{-1} }
  23
  24 % The preimage of the second argument (a set) under the first (a function).
  25 \newcommand*{\preimage}[2]{ #1^{-1}\of{#2} }
  26
  27
  28 \fi