# How to put some special diagram in the subscript of a letter?

I'm a newer by using Latex. I don't know how to code the following equation. Can you give me some helpful suggestions?

  _____              ______
|                  |
|___               |____
|    _______   .   |      ______    =0
|    |__|__|       |     |__|___|
|__|__|

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I can't really decipher what you want. Maybe you can draw a picture? –  Caramdir Jul 18 '12 at 2:44
You may wish to go to the site detexify.kirelabs.org/classify.html to look up symbols and their TeX codes. –  Mico Jul 18 '12 at 3:55
Do you want to write something like $F_{88} \cdot F_\infinity = 0$? –  Frakturfreund Jul 18 '12 at 4:17

The usual syntax of using an underscore is not limited to just text, but can be used for graphics as well. Below I have defined \BlockA and \BlockB which produce the two boxes:

If you don't provide any draw options to you get the basic:

## Code:

\documentclass{article}
\usepackage{tikz}

\begin{document}

\newcommand*{\BlockA}[1][]{%
% #1 = tikz options
\begin{tikzpicture}[scale=0.5]
\draw [#1] (0,0) rectangle (1,1);
\draw [#1] (0.5,0) -- (0.5,1.0);
\draw [#1] (0,0.5) -- (1.0,0.5);
\end{tikzpicture}
}%

\newcommand*{\BlockB}[1][]{%
% #1 = tikz options
\begin{tikzpicture}[scale=0.5]
\draw [#1] (0,0) rectangle (1.0,0.5);
\draw [#1] (0.5,0) -- (0.5,0.5);
\end{tikzpicture}
}%

$F_{\BlockA[fill=yellow]} \cdot F_{\BlockB[fill=cyan,draw=red]} = 0$
\end{document}

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That's what i want. Very very thanks! –  user16707 Jul 18 '12 at 5:11