General ⇒ How to write \phantom text backwards?

[bbasic]

I would like command similar to \phantom, but which moves not forward, but backward. See the following example:

$k+1,k+2,k+3,\dots,\overline{2k,\phantom{1}}\hspace{-2.8mm}\underbrace{1,2,3,\dots,k,}2k+1$

I would like to do this in a more elegant way than to use \hspace with negative value.

Of course, any other solutions which show how to combine \overline and \underbrace are welcomed, but I would also like to know whether there is "backwards phantom" for other purposes.

Thank you in advance.

[localghost]

There is a command \negthinspace (short form \!) which could be used here.

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$k+1,k+2,k+3,\dots,\overline{2k,\phantom{1}}\!\!\!\!\underbrace{1,2,3,\dots,k,}2k+1$

In this case the second part is placed more precisely. I don't know any other predefined negative space. But you can define your own ones.


Best regards
Thorsten¹

[gmedina]

Just a comment: 2 \negthinspace =(aprox.) 1 \negthickspace:

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\documentclass{article}
\usepackage{amsmath}

\begin{document}

$k+1,k+2,k+3,\dots,\overline{2k,\phantom{1}}\hspace{-2.8mm}\underbrace{1,2,3,\dots,k,}2k+1$

$k+1,k+2,k+3,\dots,\overline{2k,\phantom{1}}\!\!\!\!\underbrace{1,2,3,\dots,k,}2k+1$

$k+1,k+2,k+3,\dots,\overline{2k,\phantom{1}}\negthickspace\negthickspace\underbrace{1,2,3,\dots,k},2k+1$

\end{document}

Supplement:
as far as I know there are these commands for negative space:
\negthinspace (short version \!) = 3mu
\negmedspace = 4mu plus 2mu minus 4mu
\negthickspace = 5mu plus 5 mu

[Juanjo]

Here it is an alternative that doesn't use negative space:

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$k+1,k+2,k+3,\dots,\makebox[0pt][l]{$\overline{\phantom{2k,1}}$}2k,\underbrace{1,2,3,\dots,k,}2k+1$

[bbasic]

Seems that there is no way to do what I described. Thank you all anyway, especially Juanjo, whose solution is very nice and I believe that it can be adapted for most of the similar problems.