In §7 we found that analytical methods and procedures depend upon the idea of Language. One of the most popular images of Language is presenting it as a mechanism for creating, producing linguistic units. This idea was developed N. Chomsky into a special theory known as Generative or Transformational linguistics. This theory assumes that Language consists of a limited number simplest syntactical structures having no special meaning by themselves, a set of rules of rewriting, changing, transforming these simplest syntactical structures into actual sentence structures and a vocabulary filling in positions in the simplest syntactical structures and ascribing them definite meanings.
The simplest syntactical structures are called the kernel structures or deep structures, though the term "deep structure" is not exact, because it might be applied to kernel structures which already underwent some transformations or even to the kernel structures underlying the sentence and the set of transformations used to form an actual sentence out of them. The kernel or elementary syntactic structures are constructions made up of the first immediate constituent of sentences presented in the terms of classes of words.
Changes of the kernel structures or transformations can be divided into two groups. One group of transformations is employ to develop the IC's of the kernel structures including insertion of lexical elements. The other group is used to alter the kernel structures themselves, to modify the classes of IC's, and to change their relations.
The transformations of the first group can be exemplified in the following way:
S—> NP VP
NP—> DetNP
DetNP —> Det AN;
VP—>VP NP
VP—> Aux V
NP—> prpNP
prpNP—> prpDetNP
prpDetNP —> prpDet AN;
DetNP —> Det AN;
And finally:
S—>Det A N Aux V prp Det A N
Det--> my
A--> big
N--> dog
Aux--> was
V--> barking
prp--> at
Det--> a
A--> black
N--> -cat
As you may notice this set of describes results of the IC analysis. As you can see the rules demand gradual substitution of the symbols of the larger constituents by the symbols of the smaller ones till the ultimate constituents are reached and inserted. It can illustrated with the sentence we processed with the IC analysis in §7: NP-VP—>NP-Ved-Ving—>NP-Ved-Ving—> NP-Ved-Ving-prpNP—>NP-Ved-Ving-prpDetNP—> NP-Ved-Ving-prpDetANP—>He sat looking at the silent telephone
The second group of rules, those that affect the kernel structure itself, use more operations than simple substitution. The elementary operations are:
* insertion or addition — putting a new element in some of the positions of the structure, e.g. NP+VP+NP—> NP+VP+NP+prpNP (Mike took the plate—> Mike took the plate from John);
* deletion or subtraction — removing an element from the structure, e.g. NP+VP+NP+prpNP —>NP+VP+NP (Mike took the plate from John —>Mike took the plate);;
* permutation — changing the places of two or more elements of the structure, e.g. N1P+VP+N2P+N3P—> N1P+VP+N3P +N2P (John gave Mary an apple—> John gave an apple to Mary);
* substitution — changing an element in a certain position by some other element, e.g. N1P+VP +N2P +N3P —> N1P+VP+N2P+ Pron. (John gave Mary an apple—> John gave her an apple).
Strictly speaking there are only two elementary operations — insertion and deletion, because other can be represented as combinations of these two. Permutation of A+B into B+A may be described as deletion of A and insertion of A after B, or (in case we keep positions) deletion of A, inception of an additional B in A's place, deletion of the old B, insertion of a new A in old B's place. Initially these operations have a specific limitation— they cannot be applied to the lexical elements. Later the restriction was kept only for deletion and substitution This restriction was based on two assumptions: first the structures before and after transformation were considered as synonyms, and second, the transformations were thought to be applied before the lexical elements could be inserted. But rather quickly the research practice showed that lexical elements can suppress or demand certain transformations. E.g. insertion of the verb have into the structure NP1+VP+NP2 prohibits permutation of N1 and N2 and insertion of |be| and |ed|, which means that the sentences like "John has a house" cannot be turned into passive. Or another example: substitution of the noun "apple" in the sentence "Jane gave Peter an apple" by the personal pronoun "it" demands permutation of nominal elements and insertion of a preposition: " Jane gave it to Peter". These facts allowed to remove any limitations on insertion and permutation, but because deletion and substitution may radically change the meanings of structures and as a result deteriorate the procedure these operations cannot be applied to the lexical elements of the structures analysed.