My compiled math font family is not like a default one(e.g., the font used in MahtJaX), but it is same as the text font family. My example code and it's complied one are shown below.
\documentclass[xcolor=x11names,compress]{beamer}
\usepackage{graphicx}
\usepackage{tikz}
\usepackage{palatino}
\useinnertheme{default}
\usefonttheme{serif}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document}
\begin{frame}{Example}
\begin{definition}
Let $R\subseteq S\timesT$ be a relation.\break
The domain of R is defined as:\break
$\operatorname{Dom} \left({\mathcal R}\right) := \left\{{s \in S: \exists t \in T: \left({s, t}\right) \in \mathcal R}\right\}$\break
and can be denoted $\operatorname{Dom} \left({\mathcal R}\right)$.
\end{definition}
\end{frame}
\end{document}
This definition is from the webpage of Proofwiki.
How to change the font family to default for math codes in beamer?
Best Answer
The first part of this echoes Herbert's answer but I posted it as a comment 8 minutes prior to that answer and so claim this answer is legitimate ;). (But I will remove it if Herbert objects or if anybody else, not being Herbert, both objects and can give me a good reason why they have a right to object despite not being Herbert.)
Original Question
\usefonttheme{professionalfonts}
preventsbeamer
from overwriting your fonts and is therefore needed to use specified font packages.palatino
is deprecated, however.l2tabuen
recommends this replacement:An alternative would be to use TeX Gyre's Pagella, for example.
Second Question
Since this is a different question it should really be a different question. However, you could use the
description
environment rather than thedefinition
environment here.definition
always starts a new line for the main part of the definition. (The name of the term can go on the same line but the definition itself starts below.) While this could obviously be changed, it seems to me there are simpler options. For example:The Code