Unlike the substitution operation, where an entire tree is inserted below the argument node, with adjunction, only a subtree of ~ appears below the argument node; the remainder appears in its entirety above the root node of ft.
if we view the trees as descriptions, as in Figure 2, and if we take the expansion of the foot node as the main goal served by adjunction, it is not clear why the composition should have anything to say about the domination relationship between the other parts of the two objects being combined.