K-theoretic rigidity and slow dimension growth

Let A be an approximately subhomogeneous (ASH) C^∗-algebra with slow dimension growth. We prove that if A is unital and simple, then the Cuntz semigroup of A agrees with that of its tensor product with the Jiang-Su algebra Z\mathcal{Z}. In tandem with a result of W. Winter, this yields the equivalence of Z\mathcal{Z}-stability and slow dimension growth for unital simple ASH algebras. This equivalence has several consequences, including the following classification theorem: unital ASH algebras which are simple, have slow dimension growth, and in which projections separate traces are determined up to isomorphism by their graded ordered K-theory, and none of the latter three conditions can be relaxed in general.