I googled it and it seems to be a bunch of stuff about abstract sets. As someone who did ok in math at high school, I find it hard to understand why people are so obsessed with sets. They’re just collections of elements and should be very simple, right? So why do we need complicated equations to describe them?
Does ZFC have the set of all sets that don’t contain themselves, or is there a rule against that one?
Such set cannot exists under ZFC. Or rather, you cannot construct the set used in Russell’s paradox using ZFC.