In article <30bc0b39-43bc-4a66-9606-74b3ba4b137f@f5g2000vbz.googlegroups.com>, WM <mueckenh@rz.fh-augsburg.de> wrote:
> Is there some axiom or rule about permitted notation? > I must have missed that completely during nearly eight years of > intense studies of set theory. > > Regards, WM
One who only knows what you have "missed that completely" of set theory will be well on the way to being an expert at it.