J Austral Math Soc Ser A 45 pp117--126, 1988.
(Received 11 March 1987)
Let X be the d-dimensional sphere or a compact, simply connected Lie group. We define a mean-value operator analogous to the spherical mean-value operator acting on integrable functions on Euclidean space. The value of this operator will be written as M f(x, a), where x Î X and a varies over a torus A in the group of isometries of X. For each of these cases there is an interval p0 < p £ 2, where the p0 depends on the geometry of X, such that if f is in Lp(X) then there is a set of full measure in X and if x lies in this set, the function a ® M f(x, a) has some Hölder continuity on compact subsets of the regular elements of A.
1980 AMS Subject Classification: 42C10, 43A15
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