Some interactions between Hopf Galois extensions and noncommutative rings

Abstract

In this paper, our objects of interest are Hopf Galois extensions (e.g., Hopf algebras, Galois field extensions, strongly graded algebras, crossed products, principal bundles, etc.) and families of noncommutative rings (e.g., skew polynomial rings, PBW extensions and skew PBW extensions, etc.). We collect and systematize questions, problems, properties and recent advances in both theories by explicitly developing examples and doing calculations that are usually omitted in the literature. In particular, for Hopf Galois extensions we consider approaches from the point of view of quantum torsors (also known as quantum heaps) and Hopf Galois systems, while for some families of noncommutative rings we present advances in the characterization of ring-theoretic and homological properties. Every developed topic is exemplified with abundant references to classic and current works, so this paper serves as a survey for those interested in either of the two theories. Throughout, interactions between both are presented.

v1: 92 pages. v2: 91 pages; final version appearing in Universitas Scientiarum 27(2):58-148, 2022

References in corpus (9)

• Noncommutative Geometry Approach to Principal and Associated Bundles
• Galois theory for weak Hopf algebras
• Quantum torsors with fewer axioms
• Quantum torsors and Hopf-Galois objects
• Quantum heaps, cops and heapy categories
• Hopf Galois Extension in Braided Tensor Categories
• Hopf Ore Extensions
• Partial Hopf-Galois theory
• Cohen-Macaulay invariant subalgebras of Hopf dense Galois extensions