proposition: Lemma subB_def n (p q: BITS n.+1) : subB p q = fromZp (toZp p - toZp q)%R.
proof: Proof. apply toZp_inj. by autorewrite with ZpHom. Qed.
imports: HB(structures) mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq fintype tuple zmodp div) ssrextra.tuple ssrextra.nat spec spec.properties operations mathcomp(ssralg)