Products of commutators in simple algebras

Fuente: arXiv
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Autori principali: Brešar, Matej, Jang, Hau-Yuan, Robert, Leonel
Natura: Preprint
Pubblicazione: 2025
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author Brešar, Matej
Jang, Hau-Yuan
Robert, Leonel
author_facet Brešar, Matej
Jang, Hau-Yuan
Robert, Leonel
contents Let $A$ be a finite-dimensional simple algebra that is not a field. We show that every $a\in A$ can be written as $a=(bc-cb)(de-ed)$ for some $b,c,d,e\in A$. This is not always true for infinite-dimensional simple algebras. In fact, for any $m\in \mathbb N$ we provide an example of an infinite-dimensional simple unital $C^*$-algebra $A$ in which $1$ cannot be written as $\sum_{i=1}^m x_i(a_ib_i-b_ia_i)y_i$ for some $x_i,a_i,b_i,y_i\in A$.
format Preprint
id arxiv_https___arxiv_org_abs_2509_23956
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Products of commutators in simple algebras
Brešar, Matej
Jang, Hau-Yuan
Robert, Leonel
Rings and Algebras
Let $A$ be a finite-dimensional simple algebra that is not a field. We show that every $a\in A$ can be written as $a=(bc-cb)(de-ed)$ for some $b,c,d,e\in A$. This is not always true for infinite-dimensional simple algebras. In fact, for any $m\in \mathbb N$ we provide an example of an infinite-dimensional simple unital $C^*$-algebra $A$ in which $1$ cannot be written as $\sum_{i=1}^m x_i(a_ib_i-b_ia_i)y_i$ for some $x_i,a_i,b_i,y_i\in A$.
title Products of commutators in simple algebras
topic Rings and Algebras
url https://arxiv.org/abs/2509.23956