In article <email@example.com>, WM <firstname.lastname@example.org> wrote:
> On 9 Apr., 10:44, Virgil <vir...@ligriv.com> wrote: > > > > In > > > 0.1 > > > 0.11 > > > 0.111 > > > ... > > > an infinite union is *in* the sequence and an infinite union is not in > > > the sequence. > > > > How does one form unions of things which are not sets? > > Use the indices or use > 1 > 1, 2 > 1, 2, 3 > ...
How does using indices with things which are not sets allow one to to form their union?
Mathematics has perfectly clear set-theoretic definitions for the union of a family of sets but I am not aware of any set-theoretically acceptable definitions for the unions of a family of things which include non-sets. --