Definition compute_pr1_dni_first (n : nat) (i: ⟦n⟧ ) : pr1 (dni firstelement i) = S (pr1 i). Proof. intros. apply idpath. Defined.
Require Import UniMath.MoreFoundations.Tactics. Require Import UniMath.MoreFoundations.DecidablePropositions. Require Import UniMath.MoreFoundations.NegativePropositions.