Natural This type of operate signifies a partial functionality on naturals, exactly where the proof of even (n) could be noticed for a precondition. In the Cambridge English Corpus There isn't any authentic difference between the standard initial-order objects of your mathematical discourse - like naturals, sets and so on https://share.evernote.com/note/74e6f5bf-4e0f-8a5f-1a27-70e011ebb01c