data.nat ======== The natural numbers. * [basic](basic.lean) : the natural numbers, with succ, pred, addition, and multiplication * [order](order.lean) : less-than, less-then-or-equal, etc. * [bquant](bquant.lean) : bounded quantifiers * [sub](sub.lean) : subtraction, and distance * [div](div.lean) : div and mod * [gcd](gcd.lean) : gcd, lcm, and coprime * [power](power.lean) * [bigops](bigops.lean) : finite sums and products * [find](find.lean) : search for a witness to an existence statement