Past exam of the mathematics course of the University of Cambridge 2021 iii Paper 157 4 b Solution 2026-09-28
The parabolic basin is open and lies in . Suppose and let be the Fatou component containing . A small neighborhood of in meets . On one point of , the iterates eventually enter the chosen attracting petal and converge to zero along its attracting vector. Normality and the identity theorem for the limiting iterates make the same true throughout the connected component . Hence , which is impossible for a boundary point. Therefore the parabolic basin satisfies