Linear series on ribbons
Abstract
A ribbon is a double structure on P1. The geometry of a ribbon is closely related to that of a smooth curve. In this note we consider linear series on ribbons. Our main result is an explicit determinantal description for the locus Wr2n of degree 2n line bundles with at least (r+1)-dimensional sections on a ribbon. We also discuss some results of Clifford and Brill-Noether type.
0