{R : Ring@{i}} {n : nat} (i : nat) (Hi : (i < n.+1)%nat) : matrix_minor i i (identity_matrix R n.+1) = identity_matrix R n. Proof. apply path_matrix. intros j k Hj Hk. rewrite 3 entry_Build_Matrix. rapply kronecker_delta_map_inj. Defined.
Require Import Basics.Overture Basics.Trunc Basics.Tactics Basics.Decidable. Require Import Types.Sigma. Require Import Spaces.List.Core Spaces.List.Theory Spaces.List.Paths. Require Import Algebra.Rings.Ring Algebra.Rings.Module Algebra.Rings.CRing Require Import abstract_algebra. Require Import WildCat.Core WildCat.Paths. Require Import Modalities.ReflectiveSubuniverse.