# Library Coq.PArith.POrderedType

Note that the last module fulfills by subtyping many other
interfaces, such as DecidableType or EqualityType.

# OrderedType structure for positive numbers

Note that Positive_as_OT can also be seen as a UsualOrderedType
and a OrderedType (and also as a DecidableType).

# An order tactic for positive numbers

Note that p_order is domain-agnostic: it will not prove
1<=2 or x<=x+x, but rather things like x<=y -> y<=x -> x=y.