English

Birational Contractions of $\bar{M}_{3,1}$ and $\bar{M}_{4,1}$

Algebraic Geometry 2011-02-09 v2

Abstract

We study the birational geometry of Mˉ3,1\bar{M}_{3,1} and Mˉ4,1\bar{M}_{4,1}. In particular, we pose a pointed analogue of the Slope Conjecture and prove it in these low-genus cases. Using variation of GIT, we construct birational contractions of these spaces in which certain divisors of interest -- the pointed Brill-Noether divisors -- are contracted. As a consequence, we see that these pointed Brill-Noether divisors generate extremal rays of the effective cones for these spaces.

Keywords

Cite

@article{arxiv.1010.3377,
  title  = {Birational Contractions of $\bar{M}_{3,1}$ and $\bar{M}_{4,1}$},
  author = {David Jensen},
  journal= {arXiv preprint arXiv:1010.3377},
  year   = {2011}
}