English

Some remarks on stable almost complex structures on manifolds

Algebraic Topology 2016-03-22 v1

Abstract

Let XX be an (8k+i)(8k+i)-dimensional pathwise connected CWCW-complex with i=1i=1 or 22 and k0k\ge0, ξ\xi be a real vector bundle over XX. Suppose that ξ\xi admits a stable complex structure over the 8k8k-skeleton of XX. Then we get that ξ\xi admits a stable complex structure over XX if the Steenrod square Sq2 ⁣:H8k1(X;Z/2)H8k+1(X;Z/2)\mathrm{Sq}^{2}\colon H^{8k-1}(X;\mathbb{Z}/2)\rightarrow H^{8k+1}(X;\mathbb{Z}/2) is surjective. As an application, let MM be a 1010-dimensional manifold with no 22-torsion in Hi(M;Z)H_{i}(M;\mathbb{Z}) for i=1,2,3i=1,2,3, and no 33-torsion in H1(M;Z)H_{1}(M;\mathbb{Z}). Suppose that the Steenrod square Sq2 ⁣:H7(M;Z/2)H9(M;Z/2)\mathrm{Sq}^{2}\colon H^{7}(M;\mathbb{Z}/2)\rightarrow H^{9}(M;\mathbb{Z}/2) is surjective. Then the necessary and sufficient conditions for the existence of a stable almost complex structure on MM are given in terms of the cohomology ring and characteristic classes of MM.

Keywords

Cite

@article{arxiv.1603.06073,
  title  = {Some remarks on stable almost complex structures on manifolds},
  author = {Huijun Yang},
  journal= {arXiv preprint arXiv:1603.06073},
  year   = {2016}
}
R2 v1 2026-06-22T13:14:25.609Z