Representations of the space of n-theta functions

Let X be a smooth complex projective curve with group of automorphisms G. In this thesis we apply the Holomorphic Lefschetz Theorem in certain cases to compute the decomposition of the space H (J(_x),O(_n)O)) into a sum of irreducible representations of G, where J(_x) is the Jacobian variety of X and O(O) is the theta line bundle of J(_x). Namely we compute this decomposition in the cases when X is the Klein quartic curve, the Bring curve of genus 4 and the Macbeath curve of genus 7.