Current Interests:
My thesis at U.C. Berkeley dealt with Galois representations associated to modular
forms. Since then, however, my work has gravitated more toward the p-adic geometry
of modular curves. In particular, I have been working on computing the stable reduction
of the modular curve X0(pn) at the prime p
(see research statement). Due to the work of
various other people, this has been known when n<3 for over 15 years. Recently, I was
able to compute the stable reduction of X0(125) by fairly explicit
methods. Robert Coleman and I were then able to generalize that result to the case
of X0(p3). Here are some reasonable pictures of these
Stable Reduction Graphs.
I also have an enduring interest in explicit equations for modular curves.
At some point I hope to publish a semi-expository paper on the various methods for
obtaining explicit equations which I have come across and/or developed over the years.
Here is a table with some Equations for X0(N)
for a few small values of N (along with useful formulas for moduli-theoretic maps).
Research Papers:
- "Stable Reduction of X0(81)", Contemp. Math. 463 (2008), 91-109,
(preprint)
- "Stable Reduction of X0(p3)" (with R. Coleman), submitted to Algebra and Number Theory,
preprint - new as of 4/15/09
- "Fake CM and the Stable Model of X0(Np3)" (with R. Coleman),
Documenta Math. Extra Volume: John H. Coates' Sixtieth Birthday (2006), 261-300
(download)
- "Explicit Generators for Endomorphism Rings of Supersingular Elliptic Curves", joint
with Kristin Lauter, preprint posted to online
proceedings for Conference in
Honor of Harold Stark
- "Stable Model of X0(125)," LMS J. Comput. Math. 7 (2004), 21-36
(download)
- "Explicit Parameterizations of Ordinary and Supersingular Regions of
X0(pn)," Modular Curves and Abelian Varieties, Progress in
Mathematics 224, 165-179 (Birkhauser, 2004)
(download)
- "A Splitting Criterion for Galois Representations Associated to Exceptional Modular
Forms," Ph.D. thesis, U.C. Berkeley (2001) (download)
Notes and Slides from Recent Talks:
- "Stable Reduction of X0(625), with Implications," U. C. Berkeley Number Theory Seminar (S '09) (slides)
- "Eta Products and Models for Modular Curves," Heilbronn Workshop on Computations with Modular Forms (Bristol, UK, F '08) (slides)
- "Explicit Verification of a Theorem of Shimura," 22nd Annual Workshop on Automorphic Forms and Related Topics (Texas A&M, S '08) (slides)
- "Heegner Points on X0(pn)," AMS (sectional) Special Session on
Computational Arithmetic Geometry (San Francisco, 2006)
(slides)
- "Stable Reduction of X0(p3)," AMS Special Session on
Arithmetic Algebraic Geometry (Atlanta, 2005)
(slides)
- "Why Number Theorists Care About Elliptic Curves," RHIT Math Colloquium
(notes: part 1, part 2)
- "Explicit Generators for Endomorphism Rings of Supersingular Elliptic Curves,"
Conference in Honor of Harold Stark (Minneapolis, 2004)
(slides)
- "p-adic Properties of CM j-invariants." University of Rochester Number Theory
Seminar (notes: part 1,
part 2)