 In terms of a notional Elo system, if 100 points is one amateur rank, the professional levels were notionally more like 35 points apart.That in contemporary go and under modern playing conditions has been compressed down, to fewer than 30 points apart.In the Edo period, however, apprentice professionals would often be admitted as professional 1 dan at a young age (Honinbo Shusai at 13, but this was by no means young; Takagawa Kaku was admitted at 11).