Real Liouvillian Extensions of Partial Differential Fields

TL;DR

This paper develops a Galois theory for partial differential systems over real and p-adic fields, establishing existence, uniqueness, and characterizations of Picard-Vessiot extensions in these settings.

Contribution

It introduces a Galois theory framework for real and p-adic partial differential fields, including Picard-Vessiot extensions and their Galois groups, with applications to real dynamical systems.

Findings

Existence of Picard-Vessiot extensions over real and p-adic fields.

Uniqueness of these Picard-Vessiot extensions.

Characterization of real Liouvillian extensions via algebraic groups.

Abstract

In this paper, we establish Galois theory for partial differential systems defined over formally real differential fields with a real closed field of constants and over formally $p$-adic differential fields with a $p$-adically closed field of constants. For an integrable partial differential system defined over such a field, we prove that there exists a formally real (resp. formally $p$-adic) Picard-Vessiot extension. Moreover, we obtain a uniqueness result for this Picard-Vessiot extension. We give an adequate definition of the Galois differential group and obtain a Galois fundamental theorem in this setting. We apply the obtained Galois correspondence to characterise formally real Liouvillian extensions of real partial differential fields with a real closed field of constants by means of split solvable linear algebraic groups. We present some examples of real dynamical systems and indicate some possibilities of further development of algebraic methods in real dynamical systems.