THE MIDWEST NUMBER THEORY DAYS

University of Illinois at Chicago
March 7-8, 2008



Organizers:

Alina Carmen Cojocaru (UIC), Izzet Coskun (UIC),
Ramin Takloo-Bighash (UIC), and Jeremy Teitelbaum (UIC).






Schedule of Talks


The talks will take place in Lecture Center D-2 on the UIC East Campus. To get to campus, take the Blue Line train to UIC-Halsted, or walk to the intersection of Harrison and Halsted. Here are more detailed directions.

Friday, March 7, 2008
March 7
2pm - 3pm
REFRESHMENTS
March 7
3pm - 3:50pm
Winnie Li
(Penn State)
Noncongruence modular forms and modularity
March 7
3:50pm - 4:10pm
BREAK
March 7
4:10pm - 4:30pm
Steven Spallone
(Purdue)
P-adic local dynamics
March 7
4:30pm - 4:40pm
BREAK
March 7
4:40pm - 5pm
Mehmet Haluk Sengun
(Wisconsin)
Galois representations of small quadratic fields
March 7
5pm - 7pm
RECEPTION AT UIC
March 7
7:30pm
DINNER in GREEK TOWN
Saturday, March 8, 2008
March 8
9:30am - 10am
REFRESHMENTS
March 8
10am - 10:50am
Wee Teck Gan
(UC San Diego)
Formal degree and local theta correspondence
March 8
10:50am - 11:10am
BREAK
March 8
11:10am - 11:30am
Ghaith Hiary
(Minnesota)
Fast methods to compute the Riemann zeta function
March 8
11:10am - 11:40am
BREAK
March 8
11:40am- 12pm
Ling Long
(Iowa State)
On Atkin and Swinnerton-Dyer congruences of some noncongruence cuspforms
March 8
12pm - 2pm
LUNCH
March 8
2pm - 2:50pm
Noam Elkies
(Harvard)
How many points can a genus-2 curve have?
March 8
2:50pm - 3:10pm
BREAK
March 8
3:10pm - 3:30pm
Nick Ramsey
(Michigan)
The overconvergent Shimura lifting
March 8
3:30pm - 3:40pm
BREAK
March 8
3:40pm - 4pm
Maosheng Xiong
(Penn State)
The Erdos-Kac theorem for polynomials of several variables
March 8
4pm - 4:10pm
BREAK
March 8
4:10pm - 5pm
Dinesh Thakur
(Arizona)
Nature of Gamma, Zeta and Multizeta values in function field arithmetic
March 8
5pm - 6pm
CLOSING RECEPTION AT UIC
March 8
6pm - 8pm
DINNER
End





ABSTRACTS

  • Winnie Li, Noncongruence modular forms and modularity

    Unlike congruence modular forms, the arithmetic of noncongruence modular forms is not much understood, due to the lack of Hecke operators. For noncongruence forms, Atkin and Swinnerton-Dyer proposed a substitute of the familiar degree two recursive relation satisfied by congruence Hecke eigenforms by three-term congruence relations. In a certain situation, this yields very interesting congruence relations between the Fourier coefficients of congruence and noncongruence forms.
    In this survey talk, we shall review the development of noncongruence forms, discuss the progress on congruence relations, as well as the unbounded denominator conjecture, which asserts that the algebraic noncongruence forms are distinguished by its Fourier coefficients having unbounded denominators. We shall see that the modularity of certain Galois representations plays an essential role.

  • Steven Spallone, P-adic local dynamics

    We determine conjugacy classes of p-adic analytic germs of power series tangent to the identity. This is joint work with Adrian Jenkins.

  • Mehmet Haluk Sengun, Galois representations of small quadratic fields

    I will present the result that for small quadratic fields K and primes p, there is no irreducible continuous mod p representation of the absolute Galois group of K that is unramified away from p and infinity. I will discuss Serre's conjecture and its generalizations as a motivation to this result.

  • Wee Teck Gan, Formal degree and local theta correspondence

    The formal degree of a discrete series representation of a reductive group over a local field is the analog of the dimension of a finite-dimensional representation. A recent conjecture of Hiraga-Ichino-Ikeda expresses the formal degree of \pi in terms of the adjoint gamma factor of the Langlands parameter of \pi. I will explore the connection of this conjecture with Langlands functoriality and theta correspondence, and if time permits, discuss the case of GSp(4).

  • Ghaith Hiary, Fast methods to compute the Riemann zeta function

    The Riemann zeta function on the critical line can be computed using a straightforward application of the Riemann-Siegel formula, Sch\"onhage's method, or Heath-Brown's method. The complexities of these methods have exponents 1/2, 3/8 (=0.375), and 1/3 respectively. In this talk, two new fast and potentially practical methods to compute zeta are presented. One method relies on an algorithm to compute quadratic exponential (theta) sums. Its complexity has exponent 1/3. The second method employs an algorithm to compute cubic exponential sums. Its complexity has exponent 4/13 (approximately, 0.307). If time permits, I will also present the results of recent computations (with Andrew Odlyzko) of moments and other statistics of zeta. The computations were done for a set of 20*10^9 zeros near the zero 10^23, as well as at lower heights.

  • Ling Long, On Atkin and Swinnerton-Dyer congruences of some noncongruence cuspforms

    Serious investigations on modular forms for noncongruence subgroups of the modular group were pioneered by Atkin and Swinnerton. They discovered numerically the so-called three-term Atkin and Swinnerton-Dyer congruences satisfied by the Fourier coefficients of noncongruence modular forms. There are $p$-adic analogues of the three-term Hecke recursions satisfied by the classical congruence Hecke eigenforms.
    In this talk we will show that the Atkin and Swinnerton-Dyer congruences are satisfied by some special weight 4 noncongruence cuspforms. This is a joint work with A.O.L. Atkin.

  • Noam Elkies, How many points can a genus-2 curve have?

  • Nick Ramsey, The overconvergent Shimura lifting

    I'll discuss a rigid-analytic interpolation of the Shimura lifting across the eigencurve and consequences for interpolation of L values.

  • Maosheng Xiong, The Erdos-Kac theorem for polynomials of several variables

    We prove two versions of the Erdos-Kac theorem for polynomials of several variables on some varieties arising from translation and affine linear transformation.

  • Dinesh Thakur, Nature of Gamma, Zeta and Multizeta values in function field arithmetic