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Rigidity and flexibility under positive isotropic curvature
Abstract
For every n≥4 and L>0, we construct a smooth $4$-PIC metric on Sn with Urysohn $1$-width at least L and an embedded stable minimal disk of intrinsic inradius at least L. These examples disprove the proposed width and stable-disk radius bounds under a positive lower bound for isotropic curvature. On closed even-dimensional manifolds, we prove the sharp estimate λ1(2)≥(n−1)σ/2 under σ-PIC and show that equality forces roundness if a closed eigenform attaining the bound has rank at least four at some point.
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BibTeX
@misc{chow2026rigidity,
title = {{Rigidity and flexibility under positive isotropic curvature}},
author = {Tsz-Kiu Aaron Chow and Yipeng Wang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.11702},
eprint = {2609.11702},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.11702},
}
RIS
TY - UNPB
TI - Rigidity and flexibility under positive isotropic curvature
AU - Tsz-Kiu Aaron Chow
AU - Yipeng Wang
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.11702
UR - https://arxiv.org/abs/2609.11702
AB - For every n≥4 and L>0, we construct a smooth $4$-PIC metric on S^n with Urysohn $1$-width at least L and an embedded stable minimal disk of intrinsic inradius at least L. These examples disprove the proposed width and stable-disk radius bounds under a positive lower bound for isotropic curvature. On closed even-dimensional manifolds, we prove the sharp estimate λ_1^(2)≥(n−1)σ/2 under σ-PIC and show that equality forces roundness if a closed eigenform attaining the bound has rank at least four at some point.
ER -