Ghent

The classical Ingham-Karamata Tauberian theorem has many applications in different fields of mathematics, varying from number theory to $C_0$-semigroup theory and is considered to be one of the most important Tauberian theorems. We will discuss how to obtain remainder estimates in the theorem if one strengthens the assumptions on the Laplace transform. Moreover, we will give new (re­mainder) versions of this theorem under the more general one-sided Tauberian condition of $\rho(x) \ge −f(x)$ where $f$ is an arbitrary function satisfying some regularity assumptions. The talk is based on collaborative work with Jasson Vindas.

Let R be a number field (or a recursive subring of anumber field) and consider the polynomial ring R[T].

We show that the set of polynomials with integercoefficients is diophantine (existentially definable) over R[T].

Applying a result by Denef, this implies that everyrecursively enumerable subset of R[T]^k is diophantine over R[T].