Loosely speaking, there are three kinds of propositions.
Those propositions which are true and can be proved to be true.
Those propositions which are false and which can be proved to be false.
Those propositions which are true, but it can't be proved that it is true.
Here the word "proof" is used in a strict mathematical sense.
My question simply is that under which category does Riemann Hypothesis belong? Or if a bit specification is more preferred, is RH ZFC-independent?