I : I ⋅ ideal_unit R ↔ I. Proof. apply ideal_subset_antisymm. 1: apply ideal_product_subset_l. intros r p. rewrite <- rng_mult_one_r. by apply tr, sgt_in, ipn_in. Defined.
Require Import Basics Types. Require Import Spaces.Finite.Fin. Require Import Classes.interfaces.canonical_names. Require Import Algebra.Rings.Ring. Require Import Algebra.Groups.Subgroup. Require Import Algebra.AbGroups. Require Import WildCat.Core. Module Import Notation.