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