fact: Definition is_upper_triangular_partial { m n k : nat } (mat : Matrix R m n) := ∏ (i : ⟦ m ⟧%stn ) (j : ⟦ n ⟧%stn ), (stntonat _ i > (stntonat _ j)) -> i < k -> (mat i j) = 0%rig.
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