By looking at the posts on Mathematics Stack Exchange I have figured out how to produce an inset of math equations, like this:
$S=\{1,2,3\ldots \text{ n for }n\in \mathbb{N}\}\\ Y_{i,j}=\{i|i\in \mathbb{N}\land j|j\in \mathbb{N}\}$
The result that you see, a light grey box to the left of inset equations, is begun by putting a > just before the $ and concluding with an extra return at the end. I have searched the internet the world over and failed to find this feature documented. Can someone please point me to some documentation? If this is a LaTeX feature, I can't find that either.