Arens products for some convolution algebras of measures

We consider the measure algebra of a Chébli-!Trimèche hypergroup (in particular, double coset spaces of classical Lie groups) and study the corresponding Arens products on its second dual. The behaviour turns out to be different to the group case investigated in [LNPS]. For this, we study more closely properties of the multiplication and generalized translation in a Chébli-!Trimèche hypergroup and the asymptotic behaviour.