“…However, due to the complexity of the model class, there is still no corresponding thorough theoretical analysis/understanding available. To close the gap between theory and practice two simplified "training" models have been proposed and analyzed in a great number of works: vector factorization [38,75,68,71,45,18] and matrix factorization [1,2,17,29,30,32,35,36,52,53,57,61,64,70,72]. Essentially, all of these works agree in the point that, if initialized close to zero and applied to a plain least-squares formulation of factorized shape, cf.…”