Spacing in \colon

Question

Following this question the consistent way to write a function is f\colon A\to B, but if I want to write a cospan like the following

\documentclass[border=1mm]{standalone}
\usepackage{mathtools}

\begin{document}
\(0\colon 1\to I\leftarrow 1\colon 1\)
\end{document}

it gives this result in which the second \colon has not the correct spacing. So, is there a way to be consistent with the document and have correct spacing?

Answer 1

You can use the \noloc command I defined for a similar purpose

\newcommand\noloc{%
  \nobreak
  \mspace{6mu plus 1mu}
  {:}
  \nonscript\mkern-\thinmuskip
  \mathpunct{}
  \mspace{2mu}
}

Full example:

\documentclass{article}
\usepackage{amsmath}

\newcommand\noloc{%
  \nobreak
  \mspace{6mu plus 1mu}
  {:}
  \nonscript\mkern-\thinmuskip
  \mathpunct{}
  \mspace{2mu}
}

\begin{document}

\(0\colon 1\to I\leftarrow 1\noloc 1\)

\end{document}