Nonexistence of the metric with positive intermediate curvatures on manifolds with boundary
Jingche Chen, Han Hong
TL;DR
This work develops curvature obstruction techniques for compact manifolds with boundary, proving that in dimensions $2\le n\le 7$ and for $1\le m\le n-1$, no metric with positive $m$-intermediate curvature $C_m>0$ exists when the boundary is $m$-convex and a Lefschetz dual cup product of $m$ first cohomology classes remains nonzero on the boundary. The authors introduce stable free boundary weighted $m$-slicings and free boundary $\mu$-bubbles to derive integral obstructions, and they establish rigidity results showing isometric splitting under nonnegativity assumptions. A key extension demonstrates that the obstruction persists under interior or boundary connected sums with arbitrary manifolds, proved via infinite cyclic covers and weighted slicings on $\hat{Y}$. The results generalize prior Geroch-type obstructions to manifolds with boundary and provide both nonexistence and rigidity phenomena in low dimensions, with implications for the geometry and topology of bounded spaces under curvature constraints.
Abstract
We establish curvature obstruction theorems for manifolds with boundary. Our main theorems show that, for dimensions up to 7, a topologically nontrivial compact manifold with boundary cannot have a metric of positive $m$-intermediate curvature if the boundary is $m$-convex, and some rigidity result holds if $m$-intermediate curvature is nonnegative. This non-existence persists after performing a connected sum with an arbitrary manifold. These results generalize results of \cite{brendle,chenshuli,ChuKwongLee,Xu} to manifold with boundary.
