proposition: Lemma pidl_gleP i j: gle (prod_of_relation r1 r2) i j <-> [/\ pairp i, pairp j, gle r1 (P i) (P j) & gle r2 (Q i) (Q j)].
proof: Proof. apply:prod_of_rel_P. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)