Transformational Grammar - Transformations

Transformations

The usual usage of the term 'transformation' in linguistics refers to a rule that takes an input typically called the Deep Structure (in the Standard Theory) or D-structure (in the extended standard theory or government and binding theory) and changes it in some restricted way to result in a Surface Structure (or S-structure). In TGG, Deep structures were generated by a set of phrase structure rules.

For example, a typical transformation in TG is the operation of subject-auxiliary inversion (SAI). This rule takes as its input a declarative sentence with an auxiliary: "John has eaten all the heirloom tomatoes." and transforms it into "Has John eaten all the heirloom tomatoes?" In their original formulation (Chomsky 1957), these rules were stated as rules that held over strings of either terminals or constituent symbols or both.

X NP AUX Y X AUX NP Y

(where NP = Noun Phrase and AUX = Auxiliary)

In the 1970s, by the time of the Extended Standard Theory, following the work of Joseph Emonds on structure preservation, transformations came to be viewed as holding over trees. By the end of government and binding theory in the late 1980s, transformations are no longer structure changing operations at all; instead they add information to already existing trees by copying constituents.

The earliest conceptions of transformations were that they were construction-specific devices. For example, there was a transformation that turned active sentences into passive ones. A different transformation raised embedded subjects into main clause subject position in sentences such as "John seems to have gone"; and yet a third reordered arguments in the dative alternation. With the shift from rules to principles and constraints that was found in the 1970s, these construction-specific transformations morphed into general rules (all the examples just mentioned being instances of NP movement), which eventually changed into the single general rule of move alpha or Move.

Transformations actually come of two types: (i) the post-Deep structure kind mentioned above, which are string or structure changing, and (ii) Generalized Transformations (GTs). Generalized transformations were originally proposed in the earliest forms of generative grammar (e.g., Chomsky 1957). They take small structures, either atomic or generated by other rules, and combine them. For example, the generalized transformation of embedding would take the kernel "Dave said X" and the kernel "Dan likes smoking" and combine them into "Dave said Dan likes smoking." GTs are thus structure building rather than structure changing. In the Extended Standard Theory and government and binding theory, GTs were abandoned in favor of recursive phrase structure rules. However, they are still present in tree-adjoining grammar as the Substitution and Adjunction operations, and they have recently re-emerged in mainstream generative grammar in Minimalism, as the operations Merge and Move.

In generative phonology, another form of transformation is the phonological rule, which describes a mapping between an underlying representation (the phoneme) and the surface form that is articulated during natural speech.