The SOT-closure of the set of 2-isometries

Fuente: arXiv
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Auteur principal: Scherer, Marcel
Format: Preprint
Publié: 2025
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author Scherer, Marcel
author_facet Scherer, Marcel
contents We show that the set of $2$-isometries on an infinite-dimensional Hilbert space is not closed in the strong operator topology. In fact, we prove that its SOT-closure coincides with the set of all expansive operators.
format Preprint
id arxiv_https___arxiv_org_abs_2509_05083
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The SOT-closure of the set of 2-isometries
Scherer, Marcel
Functional Analysis
47A05 (Primary), 47A20 (Secondary)
We show that the set of $2$-isometries on an infinite-dimensional Hilbert space is not closed in the strong operator topology. In fact, we prove that its SOT-closure coincides with the set of all expansive operators.
title The SOT-closure of the set of 2-isometries
topic Functional Analysis
47A05 (Primary), 47A20 (Secondary)
url https://arxiv.org/abs/2509.05083