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math.DG2026
Orbit stratifications and smooth topology of positively curved six-manifolds with rank-one nonabelian symmetry
Minbo Gao, Yuhang Liu
We study closed simply connected six-manifolds with positive sectional curvature and an effective isometric action of or . Starting from Liu's corrected orbit-space…
math.DG2026
Curvature Sign Rigidity and Sharp Pointwise Pinching Thresholds
Minbo Gao, Yuhang Liu, Genyuan Zhang
We study connected Riemannian manifolds on which either the sectional curvature or the Ricci tensor is, at each point, strictly positive, strictly negative, or zero, and ask whethe…