proposition: Lemma subB_equiv_addB_negB n (p q: BITS n): subB p q = addB p (negB q).
proof: Proof. destruct n; first apply trivialBits. 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)