Pointed Hurwitz--Brill--Noether theory

Abstract

We study the geometry of Hurwitz--Brill--Noether spaces with vanishing conditions at a totally ramified point. Degeneration to a curve with an elliptic tail simplifies the combinatorics of Larson, Larson--Larson--Vogt, and Aggarwal, giving inductive proofs of Aggarwal's results in the one-point setting, and yields an efficient recursion for the algebraic Euler characteristics. Finally, when the expected dimension is negative, we give a numerical criterion ensuring the universal Hurwitz--Brill--Noether locus admits a component of expected relative dimension, generically finite over its image in the Hurwitz space, analogous to the existing results of Pflueger and Teixidor i Bigas for classical Brill--Noether loci.

arXiv comment51 pages, 8 figures, 2 tables. Comments welcome!