English
The charmatrix commutes with entrywise ring homomorphisms: charmatrix(M.map f) = charmatrix(M).map (Polynomial.map f).
Русский
Характеристическая матрица коммутирует отображение по входам матрицы: charmatrix(M.map f) = charmatrix(M).map (Polynomial.map f).
LaTeX
$$$\operatorname{charmatrix}(M.map f) = \bigl(\operatorname{charmatrix}(M)\bigr).map (\operatorname{Polynomial.map} f)$$
Lean4
theorem charmatrix_map (M : Matrix n n R) (f : R →+* S) :
charmatrix (M.map f) = (charmatrix M).map (Polynomial.map f) :=
by
ext i j
by_cases h : i = j <;> simp [h, charmatrix, diagonal]