NTS ABSTRACT

Return to NTS Spring 2016

Jan 28

Nigel Boston

The 2-class tower of Q(√-5460)

What is the liminf of the root-discriminants of all number fields? It's known (under GRH) to lie between 44.8 and 82.1. I'll explain how trying to tighten this range leads us to ask whether the 2-class tower of Q(√-5460) is finite or not and I'll describe how we find ways to address this question despite repeated combinatorial explosions in the calculation. This is joint work with Jiuya Wang.

Feb 04

Shamgar Gurevich

Low Dimensional Representations of Finite Classical Groups

Group theorists have established many formulas that express interesting properties of a finite group in terms of sums of characters of the group. An obstacle to applying these formulas is lack of control over the dimensions of representations of the group. In particular, the representations of small dimension tend to contribute the largest terms to these sums, so a systematic knowledge of these small representations could lead to proofs of some of these facts. This talk will discuss a new method for systematically constructing the small representations of finite classical groups. I will explain the method with concrete examples and applications. This is part from a joint project with Roger Howe (Yale).

Feb 18

Padmavathi Srinivasan

Conductors and minimal discriminants of hyperelliptic curves with rational Weierstrass points

Conductors and minimal discriminants are two measures of degeneracy of the singular fiber in a family of hyperelliptic curves. In the case of elliptic curves, the Ogg-Saito formula shows that (the negative of) the Artin conductor equals the minimal discriminant. In the case of genus two curves, equality no longer holds in general, but the two invariants are related by an inequality. We investigate the relation between these two invariants for hyperelliptic curves of arbitrary genus.