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arXiv · 2504.17168

The Nilpotency of the Nil Metric $\mathbb{F}$-Algebras

Antonio de França
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Abstract

Let $\mathbb{F}$ be a normed field. In this work, we prove that every nil complete metric $\mathbb{F}$-algebra is nilpotent when $\mathbb{F}$ has characteristic zero. This result generalizes Grabiner's Theorem for Banach algebras, first proved in 1969. Furthermore, we show that a metric $\mathbb{F}$-algebra $\mathfrak{A}$ and its completion $C(\mathfrak{A})$ satisfy the same polynomial identities, and consequently, if $\mathsf{char}(\mathbb{F})=0$ and $C(\mathfrak{A})$ is nil, then $\mathfrak{A}$ is nilpotent. Our results allow us to resolve K\"othe's Problem affirmatively for complete metric algebras over normed fields of characteristic zero.

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Antonio de França. 2025-04-24. The Nilpotency of the Nil Metric $\mathbb{F}$-Algebras. https://doi.org/10.1142/s0219498827501106

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