# ignore subscripts or hide subscripts

Is there a way to define a command in a way, that a possible subsequent subscript is hidden? something like

\newcommand{\mycommand}[1]{#1\nosubscript}

analogously to math operators and \limit if i want the subscript below.

The background is, that I want to be able to define commands for beamer with overlays, that do not show the subscripts at all on specific slides. I try to avoid having to include the subscripts as parameters of the commands.

What I would like to achieve, is for example a redefined command \underbrace with an overlay specification, such that

$\underbrace<3>{x < 0}_{x \text{ negative}}$

will display the underbrace including its subscript only at on specified overlays, and just x < 0 otherwise.

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Do you really need to keep the syntax? Something like \xunderbrace<3>{x<0}{x \text{ negative}} is easier to implement and as good to input. –  egreg Jun 21 '12 at 13:45

Just defining

\def\mycommand#1_#2{#1}

should do the trick.

If you use

\usepackage[intlimits]{amsmath}

you don't need \limits for sums and the above works there too.

Combining my above try and Claudio's idea you should be able to do:

\def\uncoversubscript<#1>#2_#3%
{#2_{\uncover<#1>{#3}}}
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Thank you. I'm afraid I didn't state what I need appropriately, my apologies. I edited my Question. –  IARI Jun 21 '12 at 8:07

A first trial is:

\newcommand<>{\uncoversubscript}[2]{#1_{\uncover#3{#2}}}

Example:

\documentclass{beamer}

\usepackage{amsmath,amssymb}
\newcommand<>{\uncoversubscript}[2]{%
#1_{\uncover#3{#2}}}

\begin{document}
\begin{frame}{Test}
$\uncoversubscript<2>{x}{y} \uncoversubscript<2>{z}{1}$
\end{frame}
\end{document}

Frames of the result:

Second attempt (not perfect):

\documentclass{beamer}

\usepackage{amsmath,amssymb}

% code by canaaerus
\def\uncoversubscript<#1>#2_#3%
{#2_{\uncover<#1>{#3}}}

% code by Hendrik Vogt - http://tex.stackexchange.com/a/5465/13304
\makeatletter
\let\saved@underbrace\underbrace
\renewcommand<>*\underbrace[1]{\@ifnextchar_{\ub@with<2>{#1}}{\ub@without{#1}}}
\def\ub@with<#1>#2_#3{\mathpalette\underbrace@i{{#2}_{\only<#1>{#3}}}}
\newcommand*\ub@without[1]{\mathpalette\underbrace@i{{#1}{}}}
\newcommand*\underbrace@i[2]{\underbrace@ii#1#2}
\newcommand*\underbrace@ii[3]{\saved@underbrace{#1#2}#3}
\makeatother

\begin{document}
\begin{frame}{Test}
$\uncoversubscript<2->x_y \hspace*{2cm} \underbrace{x}_{y}$

\end{frame}
\end{document}

I mess how to pass here \renewcommand<>*\underbrace[1]{\@ifnextchar_{\ub@with<2>{#1}}{\ub@without{#1}}} the current overlay specification to change <2>.

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Thank you, but that includes the subscript within the command, so it can't be used as stated in the example with underbrace –  IARI Jun 21 '12 at 8:33