Varieties of group-graded algebras of proper central exponent greater than two

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Main Authors: Benanti, F. S., Valenti, A.
Format: Preprint
Published: 2025
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_version_ 1866908360262025216
author Benanti, F. S.
Valenti, A.
author_facet Benanti, F. S.
Valenti, A.
contents Let $F$ be a field of characteristic zero and let $ \mathcal V $ be a variety of associative $F$-algebras graded by a finite abelian group $G$. To a variety $ \mathcal V $ is associated a numerical sequence called the sequence of proper central $G$-codimensions, $c^{G,δ}_n(\mathcal V), \, n \ge 1.$ Here $c^{G,δ}_n(\mathcal V)$ is the dimension of the space of multilinear proper central $G$-polynomials in $n$ fixed variables of any algebra $A$ generating the variety $\mathcal V.$ Such sequence gives information on the growth of the proper central $G$-polynomials of $A$ and in \cite{LMR} it was proved that $exp^{G,δ}(\mathcal V)=\lim_{n\to\infty}\sqrt[n]{c_n^{G,δ}(\mathcal V)}$ exists and is an integer called the proper central $G$-exponent. The aim of this paper is to characterize the varieties of associative $G$-graded algebras of proper central $G$-exponent greater than two. To this end we construct a finite list of $G$-graded algebras and we prove that $exp^{G,δ}(\mathcal V) >2$ if and only if at least one of the algebras belongs to $\mathcal V$. Matching this result with the characterization of the varieties of almost polynomial growth given in \cite{GLP}, we obtain a characterization of the varieties of proper central $G$-exponent equal to two.
format Preprint
id arxiv_https___arxiv_org_abs_2505_07410
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Varieties of group-graded algebras of proper central exponent greater than two
Benanti, F. S.
Valenti, A.
Rings and Algebras
Primary 16R10, 16R50, Secondary 16P90, 16W50
Let $F$ be a field of characteristic zero and let $ \mathcal V $ be a variety of associative $F$-algebras graded by a finite abelian group $G$. To a variety $ \mathcal V $ is associated a numerical sequence called the sequence of proper central $G$-codimensions, $c^{G,δ}_n(\mathcal V), \, n \ge 1.$ Here $c^{G,δ}_n(\mathcal V)$ is the dimension of the space of multilinear proper central $G$-polynomials in $n$ fixed variables of any algebra $A$ generating the variety $\mathcal V.$ Such sequence gives information on the growth of the proper central $G$-polynomials of $A$ and in \cite{LMR} it was proved that $exp^{G,δ}(\mathcal V)=\lim_{n\to\infty}\sqrt[n]{c_n^{G,δ}(\mathcal V)}$ exists and is an integer called the proper central $G$-exponent. The aim of this paper is to characterize the varieties of associative $G$-graded algebras of proper central $G$-exponent greater than two. To this end we construct a finite list of $G$-graded algebras and we prove that $exp^{G,δ}(\mathcal V) >2$ if and only if at least one of the algebras belongs to $\mathcal V$. Matching this result with the characterization of the varieties of almost polynomial growth given in \cite{GLP}, we obtain a characterization of the varieties of proper central $G$-exponent equal to two.
title Varieties of group-graded algebras of proper central exponent greater than two
topic Rings and Algebras
Primary 16R10, 16R50, Secondary 16P90, 16W50
url https://arxiv.org/abs/2505.07410