The University of Michigan Combinatorics Seminar
Fall 2009
October 9, 4:10-5:00, 3866 East Hall

The relations among invariants of points on the projective line

Benjamin Howard

University of Michigan


We consider the coordinate rings of GIT quotients of n points on the projective line modulo automorphisms of the line. In particular we wish to describe such rings by generators and relations. Kempe found generators in 1894. We describe the full ideal of relations in these generators.

This is joint work with John Millson, Andrew Snowden, and Ravi Vakil.