PreprintCC BY-NC-ND 4.0arXiv
On complemented subspaces of L1[0,1]
Abstract
We construct two complemented subspaces of L1[0,1]. The first has the Schur property but fails the Radon--Nikodým property. The second contains a copy of ℓ2 but no copy of L1[0,1]. Neither space is isomorphic to a Banach lattice. This gives a negative answer to the complemented-subspace question of Lindenstrauss and Rosenthal. A Lean 4 formalisation of the main results accompanies the paper.
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BibTeX
@misc{acuaviva2026complemented,
title = {{On complemented subspaces of $L_1[0,1]$}},
author = {Antonio Acuaviva},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.17283},
eprint = {2609.17283},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.17283},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - On complemented subspaces of L_1[0,1]
AU - Antonio Acuaviva
PY - 2026
DA - 2026/09/15
PB - arXiv
DO - 10.48550/arxiv.2609.17283
UR - https://arxiv.org/abs/2609.17283
AB - We construct two complemented subspaces of L_1[0,1]. The first has the Schur property but fails the Radon--Nikodým property. The second contains a copy of ℓ_2 but no copy of L_1[0,1]. Neither space is isomorphic to a Banach lattice. This gives a negative answer to the complemented-subspace question of Lindenstrauss and Rosenthal. A Lean 4 formalisation of the main results accompanies the paper.
ER -