Lemma stnprod_eq {n : nat} (f g: ⟦n⟧ -> nat) : f ~ g -> stnprod f = stnprod g. Proof. intros h. induction n as [|n IH]. { apply idpath. } rewrite 2? stnprod_step. induction (h lastelement). apply (maponpaths (λ i, i * f lastelement)). apply IH. intro x. apply h. Defined.
Require Import UniMath.MoreFoundations.Tactics. Require Import UniMath.MoreFoundations.DecidablePropositions. Require Import UniMath.MoreFoundations.NegativePropositions.