proposition: Lemma BQopp_negative2 x: inc x BQm -> inc (BQopp x) BQp.
proof: Proof. move => /Zo_P [xq xn]; apply/Zo_i; first by apply: QSo. by rewrite /BQopp; aw;apply/BZopp_negative2. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)