I : I + ideal_zero R ↔ I. Proof. apply ideal_subset_antisymm. 1: apply ideal_sum_smallest. 1: reflexivity. 1: apply ideal_zero_subset. apply ideal_sum_subset_l. 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.