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gitweb.michael.orlitzky.com - mjotex.git/blob - mjo-arrow.tex
2 % Things dealing with arrows in a category. Or functions, basically.
4 \ifx\havemjoarrow\undefined
8 \input{mjo-common
} % for \of, at least.
10 \ifx\operatorname\undefined
14 % The identity operator/arrow on its argument.
15 \newcommand*
{\identity}[1]{ \operatorname{id
}_
{{#1}} }
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} }
21 % The inverse of an arrow, function, or whatever.
22 \newcommand*
{\inverse}[1]{ #1^
{-
1} }
24 % The preimage of the second argument (a set) under the first (a function).
25 \newcommand*
{\preimage}[2]{ #1^
{-
1}\of{#2} }