Number Theory Seminar at the
University of South Carolina

Department of Mathematics

Number Theory Seminars since Fall 2005.

A list of all other seminars in the math department can be found here.

The seminars are held on Wednesdays from 12:00-1:00 in room LeConte 312.

Upcoming Events and Speakers

Open Dates

Previous Speakers

This Week: 

Wednesday, April 13.

Speaker: Matt Boylan, University of South Carolina

Title: Congruences for p(n), part II.
Abstract: Let l > 3 be prime.  Last week, the speaker discussed work of Ahlgren and Ono on the values of the partition function, p(n), in (l + 1)/2 "distinguished" residue classes modulo l.  In particular, for a distinguished residue class b mod l, the speaker showed via explicit construction that the generating function for p(ln + b) is an l-adic modular form of 1/2-integral weight.


Upcoming Events and Speakers:

SERMON 2011 in Savannah, GA at
Armstrong Atlantic State Universty
April 16-17, 2011


Wednesday, April 20.

Speaker: Andrew Vincent, University of South Carolina

Title: Applications of Extremal Graph Theory to Number Theory: A Theorem of Rainer Dietmann, Christian Elsholtz, Katalin Gyarmati, and Miklos Simonovits
Abstract: This is an expository talk about a theorem concerning coprime Diophantine powersets. A set A of positive integers is called a coprime Diophantine powerset if the shifted product ab + 1 of two different elements a and b of A is always a pure power, and the occurring pure powers are all coprime. The statement of the theorem is of particular interest to the analytic number theorist that is also interested in issues dealing with transcendence theory. The proof, on the other hand, depends entirely on some standard results in combinatorics, namely on Ramsey theory. The way in which this theory is utilized is delightful, in the humble but accurate opinion of the speaker.

Previous Seminar Talks:

Wednesday, April 6.

Speaker: Matt Boylan, University of South Carolina

Title: Congruences for p(n).
Abstract: Last week's talk was on congruences between values of the ordinary partition function, p(n).  This week, we will survey some results from the last 10 years on congruences of type p(An + B) = 0 mod M.


Wednesday, March 30.

Speaker: John Webb, University of South Carolina

Title: Applications of modular forms to the study of integer partitions.
Abstract: This talk will survey a collection of the speaker's recent
results on congruence properties of partition functions.  Particular attention will be placed on the methods coming from the theory of modular forms.


Wednesday, March 2.

Speaker: Jeremy Rouse, Wake Forest University

Title: On the sums of two cubes.
Abstract:
In this talk, we will classify solutions to f(x,y)3 + g(x,y)3 = x3 + y3, where f and g are homogeneous rational functions. The roots of this question appear in work of Viete in 1591, and the solution is a clever application of the theory of elliptic curves. Fans of the ring Z[e(2πi/3)] will enjoy this talk.


Wednesday, February 23.

Speaker: Michael Filaseta, University of South Carolina

Title: Four Seemingly Unrelated Problems, Part II.
Abstract: We quickly review the four different problems discussed last week and proceed
to explain how these seemingly unrelated problems are connected to each other. As noted in
last week's abstract, one of the problems is:  Is it possible to find an irrational number q such
that the infinite geometric sequence 1, q, q2, ... has 4 terms in arithmetic progression?
Last week, we indicated that the answer is, "No."  Our talk will include a fairly detailed
description of the proof of this result.


Wednesday, February 16.

Speaker: Michael Filaseta, University of South Carolina

Title: Four Seemingly Unrelated Problems.
Abstract: After putting some finishing touches on some questions asked of the speaker last week, we turn to the main (not completely unrelated) topic of this seminar.  We begin this part by discussing the history associated with four different problems that are number theoretic or combinatorial in nature. Two of these problems remain open and the other two have known solutions. Our goal this week and next is to explain how these seemingly unrelated problems are connected to each other.  To disclose a little more information, we mention one of the problems with a known solution here.  Is it possible to find an irrational number q such that the infinite geometric sequence 1, q, q2, ... has 4 terms in arithmetic progression?


Wednesday,
February 9.

Speaker: Michael Filaseta, University of South Carolina

Title: A polynomial conjecture of Turan rerevisited again
Abstract: This is a survey talk on a conjecture of Turan which asserts that
there is a constant C such that every polynomial f(x) in Z[x] is within C of
being an irreducible polynomial (meaning that there is a w(x) in Z[x] with
the sum of the absolute value of its coefficients at most C and with
f(x) + w(x) irreducible over the rationals).  We will give a history of results
on this still open conjecture, ending with a proof of a result established
by Mossinghoff and the speaker just last month.  Although some of you
will have heard related talks by Mossinghoff and have been in a course that
the speaker gave last year that included a discussion of this topic, note that the
speaker will put a slightly different perspective on the history of this
problem and introduce some new ideas for possible future
investigations.

Wednesday, February 2.

Speaker: Matthew Boylan, University of South Carolina

Title: An overview of p-adic modular forms.
Abstract: We survey Serre's classical theory of p-adic modular forms. Some of these ideas play an important role in the speaker's recent joint work with J. Webb on the l-adic fractal behavior of p(n), the ordinary partition function.


Wednesday, January 26.

Speaker: Frank Thorne, Stanford University.

Title: The Davenport-Heilbronn Theorem.
Abstract: We will consider the problem of counting number fields when ordered by
discriminant, with particular attention to the cubic case. An asymptotic
formula for the number of cubic fields was proved in a 1971 paper of
Davenport and Heilbronn, and we will discuss this proof in some detail. In
particular, we will explain how Davenport and Heilbronn reduced this to a
problem of counting lattice points, and we will explain how the same
techniques may be used to address related problems as well.
We will conclude by presenting some numerical data, obtained with
algorithms which were developed much later than 1971, and investigating
the match of the theorems to the actual data.


Friday, January 28

Speaker: Frank Thorne, Stanford University and USC.

Title: More on the Davenport-Heilbronn Theorem.
Abstract: Continued from above.


Wednesday, January 19.

Speaker: John Webb, University of South Carolina
Title: Regarding the l-adic fractal behavior of partition numbers
Abstract: Folsom, Kent, and Ono have recently proved that for any prime l and any positive integer m, values of the partition function display a certain periodicity modulo lm.  I will describe their result, give a proof for an improved "zoom rate", and discuss implications of their work.  I will also present calculations which illustrate this periodicity and suggest that this improved "zoom rate" is sharp.  This is joint work with Matt Boylan.





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