In this paper we study Hardy spaces H p S; on a complex open Ol'shanski semigroup S = G ExpiW ,w h e r e1 p 1 and is an absolute value on the involutive semigroup S . For 1 p 1 we p r o ve the existence of an isometric boundary value map H p S; ! L p G generalizing the corresponding result ofOl'shanski f o r p = 2 and = 1 . In the second part we use the ne structure of the space H 2 S; 1 to prove the existence of a bounded holomorphic function on S whose absolute value has a unique maximum in the boudary point 1 2 G and therefore complete the proof of the approximation property o f t h e P oisson kernel and the uniqueness of G as a Shilov boundary of S whenever W does not contain a ne lines.
IntroductionLet G be a connected Lie group, g its Lie algebra, and W g an invariant o p e n convex cone whose interior consists of elements X for which Specad X iR.