In this math code:
\exists^\omega n : \alpha [0,n] \notin A
it adds some empty space before and after :.
I want to avoid/remove the space before it. How?
[Tex/LaTex] remove additional space before `:`
math-modesymbols
Related Solutions
I would use a combination of \mathrlap and \phantom to get the positioning just right. For \mathrlap you would need the mathtools package. Instead of using \vphantom{g} to get the vertical alignment correct with the other components of your URL, I used \strut, although this may be just a difference in preference.
\documentclass{scrreprt}
\usepackage[ngerman]{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{amsmath,mathtools}
\usepackage{beramono}
\begin{document}
\texttt{https://example.org/foo/id/123456789/bar/baz}
$
\mathrlap{\underbrace{\phantom{\texttt{https://example.org/foo\strut}}}_{\text{Base-URL}}}\texttt{https://example.org/foo}%
\texttt{/id/}%
\mathrlap{\underbrace{\phantom{\texttt{123456789\strut}}}_{\text{Foo-ID}}}\texttt{123456789}%
\texttt{/}%
\mathrlap{\underbrace{\phantom{\texttt{bar/baz\strut}}}_{\text{Function}}}\texttt{bar/baz}%
$
\end{document}
This works fine from a visual/typesetting perspective, but the embedded URL is not properly expanded since it is broken into pieces (for spacing purposes). If you want to maintain a clickable link (using the url package, for example), you would have to do a little more leg work. Here's one approach:
...
\usepackage{amsmath,mathtools,url}
\newcommand{\ubspace}[2]{% Correct \underbrace spacing
\makebox[\widthof{\texttt{#1\strut}}][c]{\ensuremath{\underbrace{\phantom{\texttt{#1}\strut}}_{\text{#2}}}}
}
...
\begin{document}
\texttt{https://example.org/foo/id/123456789/bar/baz}
$
\mathrlap{%
\ubspace{https://example.org/foo}{Base-URL}%
\text{\hphantom{\texttt{/id/}}}%
\ubspace{123456789}{Foo-ID}%
\text{\hphantom{\texttt{/}}}%
\ubspace{bar/baz}{Function}}%
\text{\url{https://example.org/foo/id/123456789/bar/baz}}% Correct clickable URL
$
...
The rule for a math operator is that in case it's preceded/followed by an ordinary symbol, then a thin space is inserted. This is what's wanted in cases such as
$a\log b$
where we do want a thin space before and after “log”. In a case such as
$a\log(bc)$
the space is inserted only before “log”.
I don't know why you don't want your operator to behave differently; perhaps you don't want to add parentheses and trust on the different shape of the letter for visual distinction. So here's the way:
\newcommand{\MExp}{\mathop{}\!\mathbb{E}}
If \MExp is preceded by an ordinary operator, the thin space will be inserted. However, since the empty \mathop is followed by an ordinary symbol, it would always insert a thin space, that we remove with \!.
\documentclass{article}
\usepackage{amsmath,amssymb}
\newcommand{\MExp}{\mathop{}\!\mathbb{E}}
\begin{document}
X$\MExp$ has no space
$X \MExp X$ shows space and no space
\end{document}
Best Answer
Use
\coloninstead of:.