EDIT: I've found a solution thanks to this topic: beamer over miktex 2.9 is not working with math environment In any case, thanks to everyone who posted an answer!
I'm struggling to put an integral in this presentation. Here's the code
\documentclass{beamer}
\usepackage{relsize}
\usepackage[english]{babel}
\usepackage{amsmath,amsfonts,amsthm,bm}
\title{PCA for functional data}
\author{Carlo Schiano di Cola}
\date{21/07/2020}
\begin{document}
% [..]
\begin{frame}
\frametitle{Introduction}
Some concepts from the multivariate analysis can be imported in the functional context
\LARGE
x\textsubscript{i} $\rightarrow$ x(t)
$\mu$\textsubscript{i} $\rightarrow$ $\mu$(t)
$\Sigma$\textsubscript{ij} $\rightarrow$ v(s,t)
\begin{equation}
\int_{a}^{b} x(t)y(t)dt
\end{equation}
\end{frame}
\end{document}
The error I get says only that
MikTeX Compiler Driver did not succeed
$\mu$\textsubscript{i} $\rightarrow$ $\mu$(t)
rather than more normal markup such as$\mu_{i} \rightarrow \mu(t)$
????