Hilbert's tenth problem for complex meromorphic functions in several variables

TL;DR

This paper establishes an analogue of Hilbert's Tenth Problem for fields of complex meromorphic and analytic functions, showing the definability of integers within these function fields using logical formulas.

Contribution

It introduces a new framework for expressing integers in fields of complex meromorphic and analytic functions, extending Hilbert's Tenth Problem to these complex function fields.

Findings

Integers are positive existentially definable in fields of complex meromorphic functions.

Similar definability results hold for analytic functions with a different language predicate.

The results apply to functions meromorphic or analytic on sets containing the complex plane.

Abstract

We prove an analogue of Hilbert's Tenth Problem for complex meromorphic functions. More precisely, we prove that the set of integers is positive existentially definable in fields of complex meromorphic functions in several variables over the language of rings, together with constant symbols for two of the independent variables and the set of constants, a unary relation symbol for non-zero functions, and a unary relation symbol for evaluation at a fixed point (a place). We obtain a similar result for analytic functions, where the place appears in the language as a binary predicate. In both cases, we only require the functions to be meromorphic (or analytic) on a set containing $\mathbb C$ in one of the variables (it can be germs in all the other variables).