proposition: Lemma pnatI pi rho n : [predI pi & rho].-nat n = pi.-nat n && rho.-nat n.
proof: Proof. by rewrite /pnat andbCA all_predI !andbA andbb. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(fintype div bigop)