Status of PEP's?

[Hernan M. Foffani]

[regarding Naturals include or not Zero]
...
> At Uni, my two maths profs disagreed, too.
>

I was learnt that Naturals do not include zero.
Then in math we defined "Naturals plus Zero" set as:
    N+ = N U { 0 }     # the '+' is superscripted

Afterwards we used N+ whenever we need the zero
to be part of the Dominium. Once the set was
specified in later colloquially references the
name "Naturals plus zero" was shortened as just
Naturals. We never had to forget the little '+'
though in our homeworks or tests, though.

-Hernan