How should one approach re-tagging questions after a new tag has been added? For example, I'd like to add the tag
math.stackexchange.com/questions/tagged/realcompact-spaces to the answers that already mentioned realcompact spaces but the tag didn't exist yet. Should I do it or leave those questions alone?
Let $X$ be a space and $\beta X$ denote the Stone-Cech compactification of $X$.
$X$ is realcompact if for each $p\in \beta X\setminus X$ there is a continuous $f:X\to[0,\infty)$ such that $\beta f (p)=\infty$, where $\beta f:\beta X\to[0,\infty]$ is the extension of $f$.
It is fairly easy to s...
