how to write maximize over multiple conditions

Question

All,

I know how to write an equation if I am maximizing over one condition. For example,

$\max_{0 \leq x \leq 1} f(x)$

But I an not sure how to write it if I have to maximize the function over two conditions and I would like the second condition to appear below the first condition. Any help is appreciated.

Answer 1

You can use \substack, provided by the amsmath package:

\documentclass{article}
\usepackage{amsmath}% http://ctan.org/pkg/amsmath
\begin{document}
\[
  \max_{0 \leq x \leq 1} f(x)
\]

\[
  \max_{\substack{0 \leq x \leq 1 \\ a \geq y \geq b}} f(x)
\]
\end{document}​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

It works similar to an array where multiple lines are separated using \\. Another alternative would be to use the \mathop - it produces the same result as above:

\documentclass{article}
\usepackage{amsmath}% http://ctan.org/pkg/amsmath
\begin{document}
\[
  \mathop{\max_{0 \leq x \leq 1}}_{a \geq y \geq b} f(x)
\]
\end{document}​

\mathop makes it's argument an operator, which allows for the traditional limit placement using _ and/or ^ which adds it below/above the operator.