proposition: Fact unitZPl m n : (n * m = 1)%R -> m \is a unitZ.
proof: Proof. case: m n => [|[m|m|]|[m|m|]] [|n|n] //= []; lia. Qed.
imports: Coq(ZArith) HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(div choice fintype tuple finfun bigop finset prime) mathcomp(order binomial ssralg countalg ssrnum ssrint) mathcomp(zify_ssreflect)