Frank Schreyer's Lectures at Oberwolfach Lecture 1: Groebner Basics -> Ideal Membership Problem * Easy in 1-variable * Easy to get messed up trying in 2 (or more) variables * Notion of monom order -> Monomial orders * Lexicographic, real weights, degree reverse lexicographic * A monom order is artinian (uses Dixon's Lemma) * Leading term of a polynomial -> Division with remainder of a polynomialk by a list. * Its dependancy on the order of the f_i -> Definition of a Groebner basis in terms of the LT(ideal) * Proposition. Division algorithm works for Groebner bases, "A Groebner basis provides a solution to ideal membeship problem" * Gordan's proof of the Hilbert Basis Theorem -> Detection of Groebner bases * Definition of S-pairs (motivated for detection of new monomials in Lt(I)). * Buchberger's Criterion -- proof uses free module Groebner bases, and begins to give information about syzygies -> Definition of (first) syzygy module A finitely generated k[x1,..,xn] module has a finite free resolution -> Application: Hilbert function is a polynomial (eventually) Exercise: Let P^d x P^e ---> P^{de+d+e} be the Segre embedding (xi) x (yj) |---> (zij = xi*yj) Exercise: Show the 2x2 minors of the matrix (zij) are a GB. For Small d and e, compute the Hilbert resolution (by hand) ____________________________________________________________________ Lecture 2: W^r_d(C) = set of line bundles of degree d on C with at least r+1 sections (Subset of Jacobian) Brill-Noether Theory implies that its dimension is at least g-(r+1)(g-d+r) = rho(g, r, d) For a general curve this is an equality and W^r_d - W^{r+1}_d is smooth. Idea is to use W^r_d to dominate M_g for rho as big as possible g<= 10, a plane curve model works. Can find a family linear series over a family of plane curves, giving a unirational parametrization of M_g --> This fails for g=11. We try space curves. (Degree 12, genus 11) There could be a curve of this degree with 6 generators of its ideal in degree 5. Finding one such curve (with the right ranks of maps between higher cohomology of C and its ideal sheaf) will imply the general one has these data, and then that this rational family dominates M_11.