Extremal effective divisors of Brill-Noether and Gieseker-Petri type in ${\overline{\mathcal{M}}}_{1,n}$

Abstract

We show that certain divisors of Brill-Noether and Gieseker-Petri type span extremal rays of the effective cone in the moduli space of stable genus one curves with $n$ ordered marked points. In particular, they are different from the infinitely many extremal rays found in \cite{ChenCoskun}.

12 pages, comments are welcome!