proposition: Lemma BQinv_mon a b: inc a BQps -> inc b BQps -> (\1q /q a <=q \1q /q b <-> b <=q a).
proof: Proof. move => pa pb; move:(BQps_sBQ pa)(BQps_sBQ pb)=> pa' pb'. by move: (BQdiv_Mlelege0 QS1 pa QS1 pb); rewrite BQprod_1l // BQprod_1r //. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)