proposition: Lemma BQsum_Mltlt0 a b c : a <q c -> b <q \0q -> (a +q b) <q c.
proof: Proof. by move => pa pb; move: (BQsum_Mltlt pa pb); rewrite (BQsum_0r (proj32_1 pa)). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)