Minimal affine coordinates for SL(3,C) character varieties of free groups

Let Xr be the moduli of SL(3,C) representations of a rank r free group. In this paper we determine minimal generators of the coordinate ring of Xr. This at once gives explicit global coordinates for the moduli and determines the dimension of the moduli's minimal affine embedding. Along the way, we utilize results concerning the moduli of r-tuples of matrices in gl(3,C). Consequently, we also state general invariant theoretic correspondences between the coordinate rings of the moduli of r-tuples of elements in gl(n,C), sl(n,C), and SL(n,C).