IMPRIMITIVITY FOR C-ASTERISK-COACTIONS OF NON-AMENABLE GROUPS

We give a condition on a full coaction (A, G, delta) of a (possibly) n on-amenable group G and a closed normal subgroup N of G which ensures that Mansfield imprimitivity works; i.e. that A x (delta\)G/N is Morit a equivalent to Ax(delta)Gx(<(delta)over cap>,r)N. This condition obta ins if N is amenable or delta is normal. It is preserved under Morita equivalence, inflation of coactions, the stabilization trick of Echter hoff and Raeburn, and on passing to twisted coactions.