On 20 Mrz., 22:13, Virgil <vir...@ligriv.com> wrote: > In article > <f9fdc960-d9af-4efe-9e88-4ad45e2e8...@bs5g2000vbb.googlegroups.com>, > > WM <mueck...@rz.fh-augsburg.de> wrote: > > On 20 Mrz., 21:11, Virgil <vir...@ligriv.com> wrote: > > > > While WM may not be aware of the fine points of English, when he speaks > > > of "THE last line", in standard English it suggest that there is a last > > > line. > > > Can a well-defined list have more than one last line? > > It can have less than one last line!
Then *the* last line is missing, not *a* last line as one of many. > > Both the empty set
sic: the empty set, not an empty set
> of lines/FISONs and every infinite set of > lines/FISONs when ordered by inclusion have less than one last line, > i.e., no last line at all.
Therefore all can be removed without removing the asserted contents, namely the complete set |N.