2017/04/10 by Bopp, Christian, Hoff, Michael
#13D02 #14D20 #14H45 #14J28 #Algebraic Geometry (math.AG) #FOS: Mathematics
paper · doi:10.48550/arxiv.1704.02753
For a smooth canonically embedded curve C of genus 9 together with a pencil |L| of degree 6, we study the relative canonical resolution of C⊂ X⊂ ℙ8, where X is the scroll swept out by the pencil |L|. We show that the second syzygy bundle in this resolution of C⊂ X is unbalanced. The proof reveals a new geometric connection between the universal Brill--Noether variety W19,6 and a moduli space F^\mathfrakh of lattice polarized K3 surfaces (for a certain rank 3 lattice \mathfrakh). As a by-product we prove the unirationality of F^\mathfrakh and show that W19,6 is birational to a projective bundle over a moduli space of lattice polarized K3 surfaces F^\mathfrakh' for a certain rank 4 lattice \mathfrakh' which contains \mathfrakh as a sublattice.