Definition dualelement' {n : nat} (i : ⟦ n ⟧%stn) : ⟦ n ⟧%stn. Proof. refine (make_stn n (n - 1 - i) _). apply StandardFiniteSets.dualelement_lt. now apply stn_implies_ngt0. Defined.
Require Import UniMath.Foundations.All. Require Import UniMath.MoreFoundations.All. Require Import UniMath.Combinatorics.Maybe. Require Import UniMath.Combinatorics.StandardFiniteSets. Require Import UniMath.Algebra.Domains_and_Fields. Require Import UniMath.Algebra.RigsAndRings.