We discuss the () and the () problems for trees, partial k-trees and cographs in the decision and the construction versions. Both problems for partial k-trees are solved in linear time when the number of colors is bounded by a constant and in polynomial time for an unbounded number of colors. For trees, we improve this to linear time. In contrast to that, the two problems differ in complexity for cographs. While has a linear-time decision algorithm, is shown to be NP-complete. We give polynomial-time algorithms for the corresponding enumeration problems # and # on partial k-trees and trees and for # on cographs.