Title: On the trace of powers of Algebraic integers
Speaker:  R. Thangadurai
Affiliation: Harish-Chandra Research Institute, Prayagraj
Venue: Seminar Hall, KSoM
Date and Time: June 10, 2024 [Monday] at 11:00 AM
Abstract:  Let \alpha be a non-zero algebraic integer. In this lecture, we prove an interesting characterisation for \alpha to be a root of unity, which is an extension of a classical theorem of Kronecker. Indeed, we prove that {\it if  a non-zero algebraic integer \alpha is a root of unity if and only if the sequence \left(\mathrm{Tr}_{\mathbb{Q}(\alpha)/\mathbb{Q}}(\alpha^n)\right)_{n\geq 1} is bounded. Moreover,  if the sequence \left(\mathrm{Tr}_{\mathbb{Q}(\alpha)/\mathbb{Q}}(\alpha^n)\right)_{n\geq 1} is bounded, then it is   periodic.} Thus, if a non-zero algebraic integer \alpha is not a root of unity, it is clear that the sequence \left(\mathrm{Tr}_{\mathbb{Q}(\alpha)/\mathbb{Q}}(\alpha^n)\right)_{n\geq 1} is unbounded and hence we study the growth in the next result.  Also, we introduce a problem of Polya and its extensions.