Getting arguments underneath \min in an align environment

Question

I am wondering how can I ensure that an argument gets placed underneath \min when I use an align environment.

When I use math mode and write

\[
min_{x_1,\dots x_T} 
\]

the {x_1,\dots x_T} is placed directly underneath min.

However when I use an align environment and write

\begin{align*}
  min_{x_1\dots x_T} 
\end{align*}

the {x_1,\dots x_T} is placed to the bottom left of \min.

Answer 1

The macro is \min, not min.

When you use \min in display mode (ie, within \[ \min_{<subscript>} \], or within the align environment), the subscript is placed underneath by default.

When you use \min in inline math mode (ie, with $\min_{<subscript>}$), then you need to specify \displaystyle, or \limits to get the subscript underneath.

All four below produce:

\documentclass{article}
\usepackage{amsmath}

\begin{document}
Inline mode:
$\displaystyle \min_{x_1,\dots x_T}$
$\min\limits_{x_1,\dots x_T}$

\bigskip
Display mode:
\[ \min_{x_1,\dots x_T} \]
%
\begin{align*} 
    \min_{x_1\dots x_T} 
\end{align*}
\end{document}