...of course it’s not obvious that there’s a convenient way to do this, so thank you for making me go look for one! It turns out http://unicodelookup.com/ works pretty well for this purpose. Nevermind; this is unecessary after all.
You might also take a look at Using LaTeX to render mathematics. However, the Unicode solution may be preferable in many instances, as text is less obtrusive than inserted images for simple usage.
Some way to get HTML entities (i.e. stuff like ∈ and ⊆, not stuff like and ) - or something similar—to work in comments.
You can use the Unicode characters represented by those entities directly — e.g. ∈, ⊆.
...of course it’s not obvious that there’s a convenient way to do this, so thank you for making me go look for one! It turns out http://unicodelookup.com/ works pretty well for this purpose. Nevermind; this is unecessary after all.
You might also take a look at Using LaTeX to render mathematics. However, the Unicode solution may be preferable in many instances, as text is less obtrusive than inserted images for simple usage.