How can I get a big cross to denote a generalized cartesian product?

Question

I'm trying to get a big cross which I can subscript in order to denote a generalized cartesian product (much like how \bigcup works for generalized unions). How can I accomplish this?

Answer 1

Looking in the The Comprehensive LaTeX Symbol List reveals a \bigtimes symbol defined by the mathabx package.

Answer 2

If you don't mind using a different font, kpfonts gives you the \varprod command:

\documentclass{article}
\usepackage{kpfonts}

\begin{document}

$\varprod_{i=1}^n A_i$

\[
  \varprod_{i=1}^n A_i
\]

\end{document}

I would be more inclined to use \prod to denote a generalised cartesian product, though.

Answer 3

There is a simple command for that in the mathabx package:

\documentclass{minimal}

\usepackage{mathabx}

\begin{document}
   $\bigtimes\limits_{x=1}$
\end{document}

In fact if you find another operator symbol you fancy, you can try the \limits command on it. It may actually work. :)

I hope this answers it. :)

Answer 4

I am sure others will come up with simpler solutions, but here is an overkill solution that might be useful:

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\newcommand{\Cross}{\mathbin{\tikz [x=1.4ex,y=1.4ex,line width=.2ex] \draw (0,0) -- (1,1) (0,1) -- (1,0);}}%
\begin{document}
$A \Cross B$
\end{document}

Adjust the x= and y= options to change the size, and the line width= to adjust the thickness of the line. The \mathbin ensures that correct spacing for a binary operator is placed around the symbol.

Answer 5

Might I suggest a very simple-minded approach?
Why not just use the letter "X"? Below, I inserted \sf to render the symbol more distinguishable

$${\sf X}^n_{i=1} A_i = A_1\times \cdots \times A_n$$