Lemma neghfiberdni ( n : nat ) ( i : ⟦S n⟧ ) : ¬ ( hfiber ( dni i ) i ). Proof. intros. apply ( negf ( weqhfiberdnihfiberdi n i i ) ( neghfiberdi i ) ). Defined.
Require Import UniMath.MoreFoundations.Tactics. Require Import UniMath.MoreFoundations.DecidablePropositions. Require Import UniMath.MoreFoundations.NegativePropositions.