3 papers
math.DG2026
Positive sectional curvature on homotopy nine-spheres
Zhiqi Chen, Shaoqiang Deng, Junna Ni +1
We determine which homotopy nine-spheres admit positive sectional curvature: they are precisely the four smooth types with vanishing real Dirac index. The other four admit no metri…
math.DG2026
Positive biorthogonal curvature on
Zhiqi Chen, Hui Zhang
We construct explicit Riemannian metrics with positive biorthogonal curvature on , answering a question of Bettiol. In particular, positive biorthogonal curvature on…
math.DG2023
Curvatures of metric Jordan algebras
Hui Zhang, Zaili Yan, Zhiqi Chen
In this paper, we investigate metric Jordan algebras, and follow the lines of the paper (J. Milnor: Curvatures of left invariant metrics on Lie groups. Adv. Math. (1976)). Firstly,…