I'm studying a course on probability and statistics and at some point this symbol comes up without introduction. It looks like the number one, but slightly bigger and with a double vertical line.
First time it comes up is when discussing stochastic/random variables that are neither continuous nor discreet in an example:
And somewhat later in a proof:
Anyone got an idea what this symbol represents?
EDIT: Thanks for the fast answers, I was still editing the question for better (larger) images :)