A pinching problem for symmetric spaces of rank one (Q801309)

This paper is a slight variation of some classical pinching theorems for symmetric spaces of rank one due to [\textit{J. Cheeger}, Am. J. Math. 91, 807-834 (1969; Zbl 0183.503)]. The method of proof is again essentially the same as in Cheeger's original work except for some technical refinements gleaned from Gromov's Compactness Theorem. The pinching assumption on the derivative of the curvature is, in the reviewer's opinion, unnecessarily strong.