How to change the position of underset?

Question

In the command:

\underset{t \rightarrow x}{\limsup} f(t) = \underset{t \rightarrow x}{\liminf} f(t)

I get the {t \rightarrow x} lower under the limsup then the liminf (due to the "p" in limsup).

How can I change the position of the underset?

Answer 1

A phantom could be useful:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\[
  \underset{t \rightarrow x}{\limsup} f(t) = \underset{t \rightarrow x}{\liminf\vphantom{p}} f(t)
\]

\end{document}