“…Then, recalling the definition of concavity for the function g : IR → IR, on the convex set Ω, i.e. g βz (1) + (1 − β)z (2) ≥ βg z (1) + (1 − β)g z (2) , ∀β ∈ [0, 1], ∀z (1) , z (2) ∈ Ω, and defining, for any w ∈ A(p 1 , ε), the two linear functions so that for any w (1) , w (2) ∈ A(p 1 , ε), 0 < β < 1, we obtain βc w (1) + (1 − β)c w (2) = c w (1) = c w (2) > 1.…”