On the singular sheaves in the fine Simpson moduli spaces of 1-dimensional sheaves supported on plane quartics

Abstract

In the case of the fine Simpson moduli spaces of 1-dimensional sheaves supported on plane quartics, the subvariety of sheaves that are not locally free on their support is connected, singular, and has codimension 2.

arXiv commentThe structure of the paper changed, the main result strengthened, some computations implemented in Singular