Paper 3, Section II, F
Part II, 2017
Let be a positive even integer. Consider the subspace of given by the equation , where are coordinates in , and let be the restriction of the projection map to the first factor. Show that has the structure of a Riemann surface in such a way that becomes an analytic map. If denotes projection onto the second factor, show that is also analytic. [You may assume that is connected.]
Find the ramification points and the branch points of both and . Compute the ramification indices at the ramification points.
Assume that, by adding finitely many points, it is possible to compactify to a Riemann surface such that extends to an analytic map . Find the genus of (as a function of ).