proposition: Lemma id_mat_ii {n : nat} (i : ⟦ n ⟧%stn) : (@identity_matrix R n) i i = rigunel2.
proof: Proof. unfold identity_matrix; now rewrite (stn_eq_or_neq_refl). Defined.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Combinatorics.StandardFiniteSets UniMath.Combinatorics.Vectors UniMath.Algebra.RigsAndRings UniMath.Algebra.IteratedBinaryOperations UniMath.Algebra.Matrix UniMath.Algebra.Domains_and_Fields UniMath.Algebra.GaussianElimination.Auxiliary UniMath.Algebra.GaussianElimination.Vectors