English
The eRank of a submatrix equals the eRank of the original matrix: eRank(A.submatrix em en) = eRank(A).
Русский
eRank подматрицы равен eRank исходной матрицы: eRank(A.submatrix em en) = eRank(A).
LaTeX
$$$eRank(A_{\text{submatrix }(em,en)}) = eRank(A)$$$
Lean4
@[simp]
theorem eRank_submatrix {n : Type un} (A : Matrix m n R) (em : m₀ ≃ m) (en : n₀ ≃ n) :
eRank (A.submatrix em en) = eRank A := by
simpa [-lift_cRank_submatrix] using congr_arg Cardinal.toENat <| A.lift_cRank_submatrix em en