Nam Nguyen wrote: > > On 19/04/2013 5:55 AM, Frederick Williams wrote: > > Nam Nguyen wrote: > >> > >> On 18/04/2013 7:19 AM, Frederick Williams wrote:
> > > > >>> Also, as I remarked elsewhere, "x e S' /\ Ay[ y e S' -> y e S]" doesn't > >>> express "x is in a non-empty subset of S". > >> > >> Why? > > > > It says that x is in S' and S' is a subset of S. > > How does that contradict that it would express "x is in a non-empty > subset of S", in this context where we'd borrow the expressibility > of L(ZF) as much as we could, as I had alluded before?
You really are plumbing the depths. To express that x is non-empty you have to say that something is in x, not that x is in something.
-- When a true genius appears in the world, you may know him by this sign, that the dunces are all in confederacy against him. Jonathan Swift: Thoughts on Various Subjects, Moral and Diverting