TAG Derivation as Monotonie C-Command*

The TAG adjunction operation operates by splitting a tree at one node, which we will call the adjunction site. In the resulting structure, the subtrees above and below the adjunction site are separated by, and connected with, the auxiliary tree used in the composition. As the adjunction site is thus split into two nodes, with a copy in each subtree, a natural way of formalizing the adjunction operation posits that each potential adjunction site is in fact represented by two distinct nodes. In the FTAG formalism (Vijay-Shanker, 1988) each potential adjunction site is associated with two feature structures, one for each copy. As an alternative to this operationally defined rewriting view of adjunction, Vijay-Shanker (1992) suggests that TAG derivations instead be viewed as a monotonic growth of structural assertions that characterize the structures being composed. This proposal rests crucially on the a.cisumption that the elementary trees are characterized in terms of a domination relation among nodes, and that each potential adjunction . site is represented by two nodes standing in a domination relation. Under th.is proposal, the structures a and ß in Figure 1 would be used to derive long-distance wh-movement. To adjoin ß into a, the root and foot nodes of ß are identified with the two C nodes standing in a domination relation in a (represented by the dotted line). This domination relation still holds after adjunction, as do all the other domination relations stated in defining a and ß. (In sentences in which there is no adjoining at the C' node, e.g., 'I wonder what Mary saw,' these C' nodes could collapse, preserving domination under the assumption that it is a reflexive relation.) Domination has also been argued to play a role in multi-component structures, where there is assumed to be a domination relationship between a frontier node of one cornponent and the root of the other. While the use of domination relationships is attractive in allowing us to view TAG derivations as