Lemma dualelement_sn_stn_ge_n {n : nat} (i : stn n) : i >= (dualelement (n,, natgthsnn n)). Proof. rewrite dualelement_defs_eq. simpl. rewrite (@natminuseqn _), minuseq0'. apply idpath. 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.