rattac.
Qed.
Infix "*" := ratMult : rat_scope.
Local Open Scope rat_scope.
Notation "n / d" := (RatIntro n (pos d)) : rat_scope.
Notation "0" := rat0 : rat_scope.
Notation "1" := rat1 : rat_scope.
Infix "+" := ratAdd : rat_scope.
Delimit Scope rat_scope with rat.
Notation " |  a - b |" := (ratDistance a%rat b%rat) (at level 30, a at next level, b at next level) : rat_scope.
Infix "<=" := leRat : rat_scope.
Infix "==" := eqRat (at level 70) : rat_scope.

(* Specifications: *)
Theorem le_Rat_dec : forall r1 r2,
{r1 <= r2} + {~r1 <= r2}.