“…Let us consider ω m (P ) = [A , i ] ∈ CM(R). By[13, Corollary 2], the abelian surfaces with QM (A, i) and (A , i ) are isogenous. By this, we mean that there exists an isogeny λ : A→A making, for all α ∈ O, the following diagram commutative:Write I n m = Hom Wn ((A, i), (A , i ))for the set of isogenies between (A, i)/W n and (A , i )/W n .…”