proposition: Fact addq_subdefC : commutative addq_subdef.
proof: Proof. by move=> x y; rewrite !addq_subdefE addrC [x.2 * _]mulrC. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order ssralg countalg div ssrnum) mathcomp(ssrint prime archimedean)