proposition: Theorem Bopp_involutive : forall x, Bopp (Bopp x) = x.
proof: Proof. now intros [sx|sx| |sx mx ex Hx] ; simpl ; try rewrite Bool.negb_involutive. Qed.
imports: Coq(ZArith Reals Psatz SpecFloat) Core Round Bracket Operations Div Sqrt Relative