
Re: Matheology S 224
Posted:
Apr 20, 2013 6:25 AM


Frederick Williams <freddywilliams@btinternet.com> writes:
> 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 nonempty 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 nonempty >> 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 nonempty you > have to say that something is in x, not that x is in something.
but the claim was that x *is in* a nonempty set  in this case S', which is nonempty, since x is an element of S', and S' is a subset of S.
(Much though it would be good for Nam to realise that some background set theory axioms would be kind of useful here)
 Alan Smaill

