We prove convergence results for expanding curvature flows in the Euclidean
and hyperbolic space. The flow speeds have the form F−p, where p>1 and
F is a positive, strictly monotone and 1-homogeneous curvature function. In
particular this class includes the mean curvature F=H. We prove that a
certain initial pinching condition is preserved and the properly rescaled
hypersurfaces converge smoothly to the unit sphere. We show that an example due
to Andrews-McCoy-Zheng can be used to construct strictly convex initial
hypersurfaces, for which the inverse mean curvature flow to the power p>1
loses convexity, justifying the necessity to impose a certain pinching
condition on the initial hypersurface.Comment: 18 pages. We included an example for the loss of convexity and
pinching. In the third version we dropped the concavity assumption on F.
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