On Apr 4, 10:45 pm, WM <mueck...@rz.fh-augsburg.de> wrote: > On 4 Apr., 20:57, William Hughes <wpihug...@gmail.com> wrote:
> > A collection need not share a property > > that every one of its elements has. In this case > > every one of the elements of the collection has the property > > that it can be removed without changing the union. > > The collection does not have this property. > > That is impossible if all elements can be removed.
Nope. Any single element can be removed. This does not mean the collection of all elements can be removed.