# A way of handling \left and \right brackets [duplicate]

I'm looking a way of making something like this:

\underbrace{
\left[\nabla\times
\left[\nabla\times
\left[\ldots\nabla\times
}_{
\infty\text{-times taking curl operator}
}
\mathbf{V}\right]\right]\ldots\right] = ?

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## marked as duplicate by percusse, egreg, yo', Werner, Heiko OberdiekAug 21 '13 at 5:24

Related: Left/Right across multiline equation and \left and \right in equation across multiple lines (applies to terms in different scopes as well) –  Qrrbrbirlbel Nov 10 '12 at 19:48
Three \lefts and four \rights by the way … :) –  Qrrbrbirlbel Nov 10 '12 at 19:51
I don't see a reason for \left and \right here since they don't contain anything large. Wouldn't simple \underbrace{[\nabla\times[\nabla\times[\cdots\nabla\times}_{\infty\text{-times taking curl operator}}\mathbf{V}]]\cdots] work? –  yo' Nov 11 '12 at 8:41

It's easy to achieve this inserting an appropriate \right and \left null delimiters:

\left.
\right.


The correspondent code would be:

\underbrace{
\left[\nabla\times
\left[\nabla\times
\left[\ldots\nabla\times
\right.\right.\right.
}_{
\infty\text{-times taking curl operator}
}
\mathbf{V}\left.\left.\left.\right]\right]\right]\ldots\right] = ?

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Either setting \nulldelimiterspace=0pt inside the formula or adding \kern-3\nulldelimiterspace (or \kern-4\nulldelimiterspace) help to get rid of the additional spacing by \left. or \right.. –  Heiko Oberdiek Nov 10 '12 at 19:57
As far as I see, your solution would not wrong if there were \frac{V}{W} instead of \mathbf{V}. I think that \vphantom should be used here at the proper places. –  yo' Nov 11 '12 at 8:43