FOM: Re: NFU (and an ad)
Colin Mclarty
cxm7 at po.cwru.edu
Sat Mar 21 10:53:08 EST 1998
Reply to message from holmes at catseye.idbsu.edu of Fri, 20 Mar
Nice post. If it is an ad it is also much more, and as
strongly as I support the ban on ads I think this is fine. I have
a couple of small questions to see if I am getting this right--
of course finally I should read the book.
>(3) sets have Boolean unions
>(4) sets have unions in the usual sense
>
> [4 is an infinitary version of 3]
Does this mean 4 does not imply 3? Is that due to a lack
of unordered pair sets, or something more subtle about sets of
sets?
>(5) the equality relation and the projection relations of the pair exist
Can we define a "function from a set x to a set y" in
the usual set theoretic way (a single-valued relation between
elements of x and those of y, defined for each element of x), and
conclude (from existence of the equality relation) that every
set x has a one-to-one function to V?
Colin
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