Does there exist a Riemannian metric on the $n$-sphere ($n > 2$) such that at each point some (but not every) sectional curvature is negative?
For $n=2$ it is easily seen that such a metric cannot exist.
Does there exist a Riemannian metric on the $n$-sphere ($n > 2$) such that at each point some (but not every) sectional curvature is negative?
For $n=2$ it is easily seen that such a metric cannot exist.