There are two setbuilder notations, the vertical bar and the colon. In some cases, it is better to make a choice. For example, compare
\{f \mid f\colon M \rightarrow N \text{ is continuous}\}
and
\{f : f\colon M \rightarrow N \text{ is continuous}\}.
Also,
\{x : \lvert x \rvert = 1\}
and
\{x \mid \lvert x \rvert = 1\}.
But I feel uneasy because I was not consistent with the notation. Is it OK if I use both of them in one article?
;
throughout! – Hendrik Vogt Apr 23 '13 at 15:38