proposition: Lemma slexprod_lexprod p1 p2 : slexprod p1 p2 <-> lexprod _ _ leA (fun _ => leB) (sigT_of_prod p1) (sigT_of_prod p2).
proof: Proof. now split; intros HP; destruct p1, p2; inversion HP; constructor. Qed.
imports: Relation_Definitions