L-multipliers for Noncompact Symmetric Spaces.

Let G be a real noncompact semi-simple Lie group with finite center and K a maximal compact sub-group. The symmetric space M = G/K carries a measure invariant under the action of G. The operators which map L(p)(M) continuously into itself and commute with the action of G, can be easily characterized when p = 2 or p = 1. This note gives some results on "singular integrals" which map L(p) into itself (1 < p < + infinity).