Natural This kind of operate represents a partial functionality on naturals, where the proof of even (n) could be seen like a precondition. From the Cambridge English Corpus There isn't a serious distinction between the standard 1st-order objects of your mathematical discourse - like naturals, sets and so on - https://naturalhealthproducts.water.blog/2025/09/03/buy-ayurvedic-products-online-in-india-cureayu-official-site/