What does this notation mean: $\|\cdot \|_F$ For context, this paper defines the following equation as the accuracy metric for their function:
$$ Acc(\hat{Y}) = 1-\frac{\|Y-\hat{Y}\|_F}{\|Y\|_F} $$
I assume it's probably just a weird notation the authors made up, but I want to make sure I'm not missing anything. Google has been no help, and I can't find any other mention of that symbol in the paper. Any help is appreciated!

It's very likely the Frobenius norm, sort of the fundamental norm (Euclidean norm) over matrices : https://mathworld.wolfram.com/FrobeniusNorm.html
