Recently I asked the following question, about the separability of the underlying $C^*$-algebra in the definition of $K$-homology:
As far as I understood, in order to have well behaved theory (functoriality, six term exact sequence etc) we have to assume that our $C^*$-algebra is separable. This is in contrast with $K$-theory. Some time ago I asked also the following, natural question:
So the natural continuation of those topics would be the following:
Question: which groups may be obtained as $K$-homology groups for a separable $C^*$-algebra?