proposition: Corollary stnsum_pos_0 {n : nat} (f: ⟦S n⟧ -> nat) : f firstelement ≤ stnsum f.
proof: Proof. intros. exact (stnsum_pos f firstelement). Defined.
imports: UniMath.Foundations.NaturalNumbers UniMath.MoreFoundations.Tactics UniMath.MoreFoundations.DecidablePropositions UniMath.MoreFoundations.NegativePropositions