## EVENT DETAILS AND ABSTRACT

**Colloquium**
**Title:** The Arithmetic of Power Series

**Speaker:** Frank Calegari

**Speaker Info:** University of Chicago

**Brief Description:**

**Special Note**:

**Abstract:**

A function of a complex variable P(z) which is holomorphic around z=0 has a power series expansion P(z)=sum a_n z^n. Suppose that the a_n are all integers: what restrictions does that place on the function P(z)? We explore the relationship between this problem to questions in complex analysis, number theory, and to Kleinâ€™s famous observation that not all finite index subgroups of SL_2(Z) are determined by congruence conditions.

**Date:** Wednesday, May 04, 2022

**Time:** 4:10pm

**Where:** Lunt 105

**Contact Person:** John Francis

**Contact email:** jnkf@northwestern.edu

**Contact Phone:**

Copyright © 1997-2024
Department of Mathematics, Northwestern University.