Well, this doubt is probably silly. We have a standard notation for closure of a set $E$, we denote it $\bar{E}$ or $\operatorname{cl}{E}$ and we have a notation for the interior of a set $E$ we denote it $E^\circ$ or $\operatorname{int}{E}$. Now, what about the set of limit points of the set $E$? Is there a standard notation for it? Rudin's Analysis book denotes it like $E'$, so that $\bar{E}=E\cup E'$, but is this notation a standard one?
Thanks very much in advance.
Best Answer
$E'$ is used quite frequently to denote the set of limit points of a set $E$, and that is the notation used, as you have found, by Rudin.
I don't know that there is any standard, universally adopted notation for the set of limit points of a set; but the important thing is to always be clear about how any given author (including yourself) is defining what his/her notation is intended to represent.