proposition: Lemma Z_of_BZ_mone: Z_of_BZ \1mz = (-1)%Z.
proof: Proof. by apply:BZ_of_Z_injective; rewrite (Z_of_BZ_pa ZSm1) BZ_Z_m1. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype order) mathcomp(ssrnat ssrint ssralg ssrnum div)