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Auteurs principaux: Zhang, Peiran, Tian, Roumei, Lu, Yufeng, Yang, Yixin, Zu, Chao
Format: Preprint
Publié: 2026
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Accès en ligne:https://arxiv.org/abs/2604.22284
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author Zhang, Peiran
Tian, Roumei
Lu, Yufeng
Yang, Yixin
Zu, Chao
author_facet Zhang, Peiran
Tian, Roumei
Lu, Yufeng
Yang, Yixin
Zu, Chao
contents In this paper, we study the compactness of the product and the commutator of two inner projections on the Hardy spaces over the unit disk and the polydisc. For the single-variable case, we provide a complete characterization of the compactness of the commutator of two inner projections by means of Douglas algebra. In the multivariable setting, we discover a rigidity phenomenon: on the bidisc, the product of two inner projections is compact if and only if it has finite rank, whereas on the polydisc of dimension strictly greater than two, any such compact product must be trivial.
format Preprint
id arxiv_https___arxiv_org_abs_2604_22284
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Compactness of products and commutators of inner projections
Zhang, Peiran
Tian, Roumei
Lu, Yufeng
Yang, Yixin
Zu, Chao
Functional Analysis
Primary 47B38, Secondary 42B30, 30J05
In this paper, we study the compactness of the product and the commutator of two inner projections on the Hardy spaces over the unit disk and the polydisc. For the single-variable case, we provide a complete characterization of the compactness of the commutator of two inner projections by means of Douglas algebra. In the multivariable setting, we discover a rigidity phenomenon: on the bidisc, the product of two inner projections is compact if and only if it has finite rank, whereas on the polydisc of dimension strictly greater than two, any such compact product must be trivial.
title Compactness of products and commutators of inner projections
topic Functional Analysis
Primary 47B38, Secondary 42B30, 30J05
url https://arxiv.org/abs/2604.22284