00I2 Proposition 2.30. Let 𝒜\mathcal{A} be a kk-Banach algebra. For any f∈Af\in A, one has ([Ber, Theorem 1.3.1]) ⦀f⦀sp=maxz∈𝔐(A)|f|z\vvvert f\vvvert_{\mathrm{sp}}=\max_{z\in\mathfrak{M}(A)}|f|_{z}