Natural This kind of function represents a partial purpose on naturals, wherever the proof of even (n) may be witnessed for a precondition. Within the Cambridge English Corpus There isn't a real distinction between the standard 1st-order objects with the mathematical discourse - such as naturals, sets and so on https://share.evernote.com/note/b6ac86c4-49b5-8a83-fcdd-e9f84e4317c6