Complemented subspaces of Banach spaces $C(K\times L)$

Fuente: arXiv
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Autores principales: Plebanek, Grzegorz, Rondoš, Jakub, Sobota, Damian
Formato: Preprint
Publicado: 2024
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author Plebanek, Grzegorz
Rondoš, Jakub
Sobota, Damian
author_facet Plebanek, Grzegorz
Rondoš, Jakub
Sobota, Damian
contents We prove that, for every compact spaces $K_1,K_2$ and compact group $G$, if both $K_1$ and $K_2$ map continuously onto $G$, then the Banach space $C(K_1 \times K_2)$ contains a complemented subspace isometric to the Banach space $C(G)$. Consequently, $C(K_1\times K_2)$ contains a complemented copy of $C([0,1])$ for every non-scattered $K_1,K_2$. Also, answering a question of Alspach and Galego, we get that $C(βω\timesβω)$ contains a complemented copy of $C([0,1]^κ)$ for every cardinal number $1\leκ\le{\mathfrak c}$ and hence a complemented copy of $C(K)$ for every metric compact space $K$. On the other hand, for the pointwise topology, we show that $C_p(βω\timesβω)$ contains no complemented copy of $C_p(2^ω)$.
format Preprint
id arxiv_https___arxiv_org_abs_2405_19120
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Complemented subspaces of Banach spaces $C(K\times L)$
Plebanek, Grzegorz
Rondoš, Jakub
Sobota, Damian
Functional Analysis
Primary: 46B20, 46E15. Secondary: 28A33, 46B26
We prove that, for every compact spaces $K_1,K_2$ and compact group $G$, if both $K_1$ and $K_2$ map continuously onto $G$, then the Banach space $C(K_1 \times K_2)$ contains a complemented subspace isometric to the Banach space $C(G)$. Consequently, $C(K_1\times K_2)$ contains a complemented copy of $C([0,1])$ for every non-scattered $K_1,K_2$. Also, answering a question of Alspach and Galego, we get that $C(βω\timesβω)$ contains a complemented copy of $C([0,1]^κ)$ for every cardinal number $1\leκ\le{\mathfrak c}$ and hence a complemented copy of $C(K)$ for every metric compact space $K$. On the other hand, for the pointwise topology, we show that $C_p(βω\timesβω)$ contains no complemented copy of $C_p(2^ω)$.
title Complemented subspaces of Banach spaces $C(K\times L)$
topic Functional Analysis
Primary: 46B20, 46E15. Secondary: 28A33, 46B26
url https://arxiv.org/abs/2405.19120