Picard groups of quasi-Frobenius algebras and a question on Frobenius strongly graded algebras

Fuente: arXiv
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Autori principali: Dascalescu, Sorin, Nastasescu, Constantin, Nastasescu, Laura
Natura: Preprint
Pubblicazione: 2023
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author Dascalescu, Sorin
Nastasescu, Constantin
Nastasescu, Laura
author_facet Dascalescu, Sorin
Nastasescu, Constantin
Nastasescu, Laura
contents Our initial aim was to answer the question: does the Frobenius (symmetric) property transfers from a strongly graded algebra to its homogeneous component of trivial degree? Related to it, we investigate invertible bimodules and the Picard group of a finite dimensional quasi-Frobenius algebra $R$. We compute the Picard group, the automorphism group and the group of outer automorphisms of a $9$-dimensional quasi-Frobenius algebra which is not Frobenius, constructed by Nakayama. Using these results and a semitrivial extension construction, we give an example of a symmetric strongly graded algebra whose trivial homogeneous component is not even Frobenius. We investigate associativity of isomorphisms $R^*\ot_RR^*\simeq R$ for quasi-Frobenius algebras $R$, and we determine the order of the class of the invertible bimodule $H^*$ in the Picard group of a finite dimensional Hopf algebra $H$. As an application, we construct new examples of symmetric algebras.
format Preprint
id arxiv_https___arxiv_org_abs_2309_10169
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Picard groups of quasi-Frobenius algebras and a question on Frobenius strongly graded algebras
Dascalescu, Sorin
Nastasescu, Constantin
Nastasescu, Laura
Rings and Algebras
16D50, 16D20, 16L60, 16S99, 16T05, 16W50
Our initial aim was to answer the question: does the Frobenius (symmetric) property transfers from a strongly graded algebra to its homogeneous component of trivial degree? Related to it, we investigate invertible bimodules and the Picard group of a finite dimensional quasi-Frobenius algebra $R$. We compute the Picard group, the automorphism group and the group of outer automorphisms of a $9$-dimensional quasi-Frobenius algebra which is not Frobenius, constructed by Nakayama. Using these results and a semitrivial extension construction, we give an example of a symmetric strongly graded algebra whose trivial homogeneous component is not even Frobenius. We investigate associativity of isomorphisms $R^*\ot_RR^*\simeq R$ for quasi-Frobenius algebras $R$, and we determine the order of the class of the invertible bimodule $H^*$ in the Picard group of a finite dimensional Hopf algebra $H$. As an application, we construct new examples of symmetric algebras.
title Picard groups of quasi-Frobenius algebras and a question on Frobenius strongly graded algebras
topic Rings and Algebras
16D50, 16D20, 16L60, 16S99, 16T05, 16W50
url https://arxiv.org/abs/2309.10169