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Extensions of generic measure-preserving actions

We show that, whenever Gamma is a countable abelian group and Delta is a finitely-generated subgroup of Gamma, a generic measure-preserving action of Delta on a standard atomless probability space (X,mu) extends to a free measure-preserving action of Gamma on (X,mu). This extends a result of Ageev, corresponding to the case when Delta is infinite cyclic.