B2.10

Algebraic Curves
Part II, 2003

(a) For which polynomials f(x)f(x) of degree d>0d>0 does the equation y2=f(x)y^{2}=f(x) define a smooth affine curve?

(b) Now let CC be the completion of the curve defined in (a) to a projective curve. For which polynomials f(x)f(x) of degree d>0d>0 is CC a smooth projective curve?

(c) Suppose that CC, defined in (b), is a smooth projective curve. Consider a map p:CP1p: C \rightarrow \mathbb{P}^{1}, given by p(x,y)=xp(x, y)=x. Find the degree and the ramification points of pp.