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arXiv · 1310.4987

A tower condition characterizing normality

Lars Kadison
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Abstract

We define left relative H-separable tower of rings and continue a study of these begun by Sugano. It is proven that a progenerator extension has right depth two if and only if the ring extension together with its right endomorphism ring is a left relative H-separable tower. In particular, this applies to twisted or ordinary Frobenius extensions with surjective Frobenius homomorphism. For example, normality for Hopf subalgebras of finite-dimensional Hopf algebras is also characterized in terms of this tower condition.

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Lars Kadison. 2014-01-27. A tower condition characterizing normality. https://arxiv.org/abs/1310.4987

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