Graded rings of modular forms and canonical rings of stacky curves

Series: Algebra and Number Theory Seminar
Location: ENR 2 S395
Presenter: David Zureick-Brown, Emory

We give a generalization to stacks of the classical theorem of Petri -- i.e., we give a presentation for the  canonical ring of a stacky curve. This is motivated by the following application: we give an explicit presentation for the ring of modular forms for a Fuchsian group with finite coarea, which depends on the signature of the group. This is joint work with John Voight.