# Central superscripts on \bigcup

The \bigcup symbol allows you to write an upper bound (\bigcup_{lb}^{ub}) that will be centered on the top of the cup. For my problem I'm defining a modified version of the union operator that I'd like to indicate ad \widetilde{\bigcup}, but I couldn't obtain the tilde between the cup and the upper bound

\widetilde {\bigcup_{\gamma = 1}^{n}} : puts the tilde above the n

\widetilde {\bigcup}_{\gamma = 1}^{n} : the upper bound is not centered

Any suggestion ?

• I am sorry, but I don't understand exactly what you want the result to look like. Is there an image somewhere you could point us to? – Steven B. Segletes Oct 21 '14 at 10:41
• – Peter Grill Oct 21 '14 at 23:20

This is the easiest way:

\documentclass{article}
\usepackage{amsmath}

\newcommand{\wbigcup}{\mathop{\widetilde{\bigcup}}\displaylimits}

\begin{document}
$\wbigcup_{i=1}^n A_i$
\end{document}


Note that \displaylimits is not really needed, but clarity is important.