Coherent systems of genus 0, III: Computation of flips for k=1

Abstract

In this paper we continue the investigation of coherent systems of type $(n,d,k)$ on the projective line which are stable with respect to some value of a parameter $α$. We consider the case $k=1$ and study the variation of the moduli spaces with $α$. We determine inductively the first and last moduli spaces and the flip loci, and give an explicit description for ranks 2 and 3. We also determine the Hodge polynomials explicitly for ranks 2 and 3 and in certain cases for arbitrary rank.