proposition: Lemma rmorph_eq1 x : injective f -> (f x == 1) = (x == 1).
proof: Proof. exact: rmorph_eq_nat 1%N. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)