We classify unital monomorphisms into certain simple Z-stable C^*-algebras up
to approximately unitarily equivalence. The domain algebra C is allowed to be
any unital separable commutative C^*-algebra, or any unital simple separable
nuclear Z-stable C^*-algebra satisfying the UCT such that C\otimes B is of
tracial rank zero for a UHF algebra B.
We consider a certain class of unital simple stably finite C^*-algebras which
absorb the Jiang-Su algebra Z tensorially. Under a mild assumption, we show
that the crossed product of a C^*-algebra in this class by a strongly outer
action of Z^N or a finite group is Z-stable. As an application, we also prove
that any strongly outer actions of Z^2 on Z are mutually cocycle conjugate.
For almost finite groupoids, we study how their homology groups reflect
dynamical properties of their topological full groups. It is shown that two
clopen subsets of the unit space has the same class in H_0 if and only if there
exists an element in the topological full group which maps one to the other. It
is also shown that a natural homomorphism, called the index map, from the
topological full group to H_1 is surjective and any element of the kernel can
be written as a product of four elements of finite order.