Real Liouvillian Extensions of Partial Differential Fields

• Published in: Symmetry, Integrability and Geometry: Methods and Applications
• Date: 2021
• Main Authors: Crespo, Teresa, Hajto, Zbigniew, Mohseni, Rouzbeh
• Format: Article
• Language: English
• Published: Інститут математики НАН України 2021
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/211432
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Real Liouvillian Extensions of Partial Differential Fields. Teresa Crespo, Zbigniew Hajto and Rouzbeh Mohseni. SIGMA 17 (2021), 095, 16 pages

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 -adic differential fields with a -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 -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 for further development of algebraic methods in real dynamical systems.