In article <email@example.com>, firstname.lastname@example.org wrote:
> On Saturday, 3 May 2014 20:55:10 UTC+2, Virgil wrote: > > > > There is only one such set which has no elements. the empty set, > > What elements has the set of all individually undefinable real numbers?
All but the countably many real numbers for which there can be finite individual definitions.
> Does > it differ from one of its subsets
It only need differ from its proper subsets, of which there are many.
E.g., EVERY subset of only those individually undefinable real numbers within a real interval having distinct rational endpoints will be a proper subset of the set of all individually undefinable real numbers. --