In latex, an equation inside `\bf`

is in regular font. Exported to TeXmacs, it will be in bold font.

For example, save the following in a TeX file

```
\documentclass{article}
\begin{document}
\bf The point $x=\infty$
\end{document}
```

When compiled in LaTeX, the equation is in regular font. Please see texlive.net

When imported to TeXmacs, the equation is in bold font.