We now put N = A − L. Clearly, L + N = A and LN = LA − L2 = AL − L2 = N L. Hence, it remains to show that N n = 0. As above, it is enough to show that N n x = 0 for all vectors x ∈ ker(A − λj I )αj and all j = 1, . . . , m. By definition of L and N , we have N x = Ax − Lx = (A − λj I )x for all x ∈ ker(A −λj I )αj . From this it is easy to see that N n x = (A −λj I )n x. However, (A − λj I )n x = 0 since x ∈ ker(A − λj I )αj and αj ≤ n. Thus, we conclude that N n x = 0 for all x ∈ ker(A − λj I )αj . This completes the proof of the existence part.