I want to type this equation,
however I am struggling with \mathcal and \mathbb,
Here is my code, can anyone tell me what's wrong to my code and how to fix it? Thanks!
\begin{equation}
\min _{W} \underset{(x, y) \sim \mathcal{D}}{\mathbb{E}} \mathcal{L}(W ;(x, y))
\end{equation}
What I am having is: The letter E, and D did not display as expected
Solved: the package of \usepackage{breqn} disrupted the compilation. When I remove this line, the problem is resolved.



\begin{equation}and before the\end{equation}in your code? There can't be empty blank lines in\begin{equation}...\end{equation}, the will cause errors. If I remove those lines, the following document compiles fine and without errors to what I would expect: https://gist.github.com/moewew/dd09718e521ec381cf6709095147d52e – moewe Jul 25 '21 at 10:39\mathbb{E}behave more like\minw.r.t. subscript placement. – moewe Jul 25 '21 at 10:42\usepackage{amssymb}. – egreg Jul 25 '21 at 12:28