How do I get the classical N1 object rather than N*? (NN)
Sage's global "NN" is the modern definition of the natural numbers (N0, which includes zero); how do I get instead an object representing the classical definition (N1 a.k.a. N*, which excludes zero)?
Non negative integer semiring
If I want to make further set subtractions, how do I do so? What trade-offs might I encounter typically with such operations?