Unitary S1-Manifolds with Four Fixed Points and Kosniowski's Conjecture
Abstract
We study unitary S1-manifolds with four isolated fixed points in relation to Kosniowski's conjectural inequality 4χ(M)>dim M. For every integer m≥3, we show that there exists a unitary S1-manifold Mm18 with exactly four isolated fixed points, and these manifolds are pairwise distinct and nonzero in ordinary complex bordism. Since χ(Mm18)=4, they give an infinite family of counterexamples to 4χ(M)>dim M. By gluing two blocks formed by G2/SU(3)≅ S6 and the unit disk D(V) of 12- dimensional real S1-representation V along their equivariantly identified free boundaries, we explicitly construct such a manifold M183. We also prove that the four-point case is null-bordant in real dimension 16 and in every real dimension greater than 18; hence 18 is the smallest dimension in which such a counterexample occurs.
Related
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BibTeX
@misc{lu2026unitary,
title = {{Unitary $S^1$-Manifolds with Four Fixed Points and Kosniowski's Conjecture}},
author = {Zhi Lü and Jun Ma and Qiangbo Tan},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.23855},
eprint = {2610.23855},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.23855},
}
RIS
TY - UNPB
TI - Unitary S^1-Manifolds with Four Fixed Points and Kosniowski's Conjecture
AU - Zhi Lü
AU - Jun Ma
AU - Qiangbo Tan
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2610.23855
UR - https://arxiv.org/abs/2610.23855
AB - We study unitary S^1-manifolds with four isolated fixed points in relation to Kosniowski's conjectural inequality 4χ(M)>dim M. For every integer m≥3, we show that there exists a unitary S^1-manifold M_m^18 with exactly four isolated fixed points, and these manifolds are pairwise distinct and nonzero in ordinary complex bordism. Since χ(M_m^18)=4, they give an infinite family of counterexamples to 4χ(M)>dim M. By gluing two blocks formed by G_2/SU(3)≅ S^6 and the unit disk D(V) of 12- dimensional real S^1-representation V along their equivariantly identified free boundaries, we explicitly construct such a manifold M^18_3. We also prove that the four-point case is null-bordant in real dimension 16 and in every real dimension greater than 18; hence 18 is the smallest dimension in which such a counterexample occurs.
ER -