sense. The second two trees, where the coordinator is the head, are similar to the first two insofar as the conjuncts are equi-level sisters. These two flat analyses stand in contrast to the following three layered analyses. The constituency-based a-trees appear again on the left, and the dependency-based b-trees on the right:

The primary aspect of these layered analyses is that an attempt is being made to adapt the analysis of coordinate structures to the analysis of subordinate structures.