NIU Department of Mathematical Sciences

Upcoming Colloquia and Seminars

January 20-23, 2015


Algebra Seminar:   Wednesday, Jan. 21, 4:15-5:15 p.m. in DU 152
Speaker: Deepak Naidu
Topic: Classification of Modular Categories
Abstract: Modular categories are braided fusion categories that satisfy a certain nondegeneracy condition. They give rise to representations of the modular group SL(2, Z), explaining the terminology. They arise in several areas of mathematics and physics, such as representation theory, conformal field theory, operator algebras, and topology. After giving several examples of modular categories, I will discuss the problem of classifying these objects according to their Frobenius-Perron dimension. I will present several classification results, including those for Frobenius-Perron dimensions p^n, pq^n, pqr, and p^2q^2, where n is a positive integer and p, q and r are distinct primes.

Complex Analysis Seminar:   Tuesday, Jan. 27, 11:00-11:50 p.m. in DuSable 464
Speaker: Alastair Fletcher
Topic: Structures of the Julia set
Abstract: The Julia set is the set where the iterates of a function behave chaotically. In this talk, we will discuss what topological structures can arise as Julia sets, and in particular give a construction of a uniformly quasiregular mapping in three dimensions for which the Julia set is a wild Cantor set. Joint work with Jang-Mei Wu (UIUC).

Applied Math Seminar:   Tuesday, Jan. 27, 11:30-12:20 p.m. in Watson 110
Speaker: Nathan Krislock
Topic: Semidefinite Optimization and Combinatorial Optimization
Abstract: During the last two decades, semidefinite optimization has grown into a significant field of research with applications in many diverse areas such as graph theory, distance geometry, combinatorial optimization, low-rank matrix completion, and polynomial optimization. In combinatorial optimization, semidefinite optimization is used to compute high-quality bounds to many difficult (in fact, NP-hard) problems, such as Max-Cut and maximum k-cluster. This has led to the development of state-of-the-art branch-and-bound methods for solving such problems to optimality.