Analogue of the Galois Theory for normal fields and B-extensions (characteristic free approach)

Fuente: arXiv
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Autor principal: Bavula, V. V.
Formato: Preprint
Publicado: 2025
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author Bavula, V. V.
author_facet Bavula, V. V.
contents The aim of the paper is to introduce B-extensions which are the most symmetrical finite field extensions (a finite field extension $L/K$ is called a {\it B-extension} if the endomorphism algebra ${\rm End}_K(L)$ is generated by the algebra of differential operators ${\cal D} (L/K)$ on the $K$-algebra $L$ and the automorphism group $G(L/K):={\rm Aut}_{K-{\rm alg}}(L)$) and to obtain an analogue of the Galois Theory for B-extensions. Surprisingly, the class of B-extensions coincides with the class of {\it normal } finite field extensions. As a result, an analogue of the Galois Theory is obtained for normal field extensions. In particular, all Galois field extensions and all purely inseparable field extensions are B-extensions. Our approach is a ring theoretic (characteristic free) approach which is based on central simple algebras. In this approach, analogues of the Galois Correspondences (for subfields and normal subfields of $L$) are deduced from the Double Centralizer Theorem which is applied to the central simple algebra ${\rm End}_K(L)$ and subfields of B-extensions. Since Galois finite field extensions are B-extensions, this approach gives a new conceptual (short) proofs of key results of the Galois Theory, see [2] for details. It also reveals that the `maximal symmetry' (of field extensions) is the essence of the classical Galois Theory and the analogue of the Galois Theory for normal field extensions.
format Preprint
id arxiv_https___arxiv_org_abs_2509_01779
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Analogue of the Galois Theory for normal fields and B-extensions (characteristic free approach)
Bavula, V. V.
Number Theory
11S20, 12F10, 16S32, 12F05, 12F15, 16G10
The aim of the paper is to introduce B-extensions which are the most symmetrical finite field extensions (a finite field extension $L/K$ is called a {\it B-extension} if the endomorphism algebra ${\rm End}_K(L)$ is generated by the algebra of differential operators ${\cal D} (L/K)$ on the $K$-algebra $L$ and the automorphism group $G(L/K):={\rm Aut}_{K-{\rm alg}}(L)$) and to obtain an analogue of the Galois Theory for B-extensions. Surprisingly, the class of B-extensions coincides with the class of {\it normal } finite field extensions. As a result, an analogue of the Galois Theory is obtained for normal field extensions. In particular, all Galois field extensions and all purely inseparable field extensions are B-extensions. Our approach is a ring theoretic (characteristic free) approach which is based on central simple algebras. In this approach, analogues of the Galois Correspondences (for subfields and normal subfields of $L$) are deduced from the Double Centralizer Theorem which is applied to the central simple algebra ${\rm End}_K(L)$ and subfields of B-extensions. Since Galois finite field extensions are B-extensions, this approach gives a new conceptual (short) proofs of key results of the Galois Theory, see [2] for details. It also reveals that the `maximal symmetry' (of field extensions) is the essence of the classical Galois Theory and the analogue of the Galois Theory for normal field extensions.
title Analogue of the Galois Theory for normal fields and B-extensions (characteristic free approach)
topic Number Theory
11S20, 12F10, 16S32, 12F05, 12F15, 16G10
url https://arxiv.org/abs/2509.01779