“…11 ) + ϕ(b 12 ) + ϕ(c 21 ) ∈ A ′ there exists T ∈ A such that ϕ(t) = ϕ(a 11 ) + ϕ(b 12 ) + ϕ(c 21 ), with t = t 11 + t 12 + t 21 + t 22 . Now, observing that q n * (e 2 , ..., e 2 , a 11 ) = 0 and using Proposition 1.2 and Lemma 2.3, we obtain ϕ(q n * (e 2 , ..., e 2 , t)) = ϕ(q n * (e 2 , ..., e 2 , a 11 )) + ϕ(q n * (e 2 , ..., e 2 , b 12 ))By injectivity of ϕ we have q n * (e 2 , ..., e 2 , t) = q n * (e 2 , ..., e 2 , b 12 ) + q n * (e 2 , ..., e 2 , c 21 ), that is, 2t 22 + t 12 + t 21 = b 12 + c 21 .…”