# Sub and superscript on the left

I want to do something like this:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align*}
Hom_{K\cap {}_a^bK}
\end{align*}
\end{document}


But there seems that the _a^b is on the \cap and not attached to the K.

How might I do this right?

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–  Nicholas R. Peterson Jun 13 '13 at 14:14
@nrpeterson: I did take a look at that, but I can't get that to work. Can you show me in an answer how I might do what I am trying to do? –  Thomas Jun 13 '13 at 14:42

None of the mentioned packages would give a good result in this case, because TeX suppresses space around binary operations in subscripts.

A good solution for this particular case seems to be

\documentclass{article}
\usepackage{amsmath,leftidx}
\DeclareMathOperator{\Hom}{Hom}
\begin{document}
$\Hom_{K\cap \,\leftidx{_a^b}{\!K}{}}$
\end{document}


The \, pushes right the right operand a bit, so to separate it from the intersection symbol. The K would however be too detached from the prescripts, so I add a small correction.

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