An orbit space of a nonlinear involution of 𝑆²×𝑆² with nonnegative sectional curvature

Torres, Rafael

doi:10.1090/proc/14486

An orbit space of a nonlinear involution of $S^2\times S^2$ with nonnegative sectional curvature
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Proc. Amer. Math. Soc. 147 (2019), 3523-3532 Request permission

Abstract:

We describe a construction of Riemannian metrics of nonnegative sectional curvature on a closed smooth nonorientable 4-manifold with fundamental group of order two that realizes a homotopy class that was not previously known to contain nonnegatively curved manifolds. The procedure yields new metrics of nonnegative sectional curvature on any 2-sphere bundle with base space the 2-sphere or the real projective plane.

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