Subordination (linguistics) - Representing Subordination and Coordination

Representing Subordination and Coordination

Most theories of syntax represent subordination (and coordination) in terms of tree structures. A head is positioned above its dependents in the tree, so that it immediately dominates them. One of two competing principles is employed to construct the trees: either the constituency relation of phrase structure grammars or the dependency relation of dependency grammars. Both principles are illustrated here with the following trees. The a-trees on the left illustrate constituency, and the b-trees on the right dependency:

Constituency shows subordination by way of projections. One of the two words projects its category status up to the root node of the entire structure and is therefore the head of the structure. Dependency also shows subordination, but it does so with fewer nodes in the tree. The head directly dominates its dependent. These trees illustrating subordination can be compared with trees illustrating coordination. There are various proposals concerning the tree representations of coordinate structures. The following trees are just suggestive in this regard. The constituency relation is again shown in the a-trees on the left, and the dependency relation in the b-trees on the right:

The constituency trees show that both parts of the coordinate structure project up to the root node of the entire tree, and the dependency trees illustrate that each word again projects just a single node. Both representation formats illustrate the equal status of the coordinated units insofar as they are placed on the same level; they are equi-level. From an organizational point of view, subordination is grouping words together in such a manner that includes hierarchical and linear order, whereas coordination is grouping words together just in terms of linear order.