TRANSFORMATIONAL GRAMMARS

Further research revealed great generality, mathematical elegance, and wide applicability of generative grammars. They became used not only for description of natural languages, but also for specification of formal languages, such as those used in mathematical logic, pattern recognition, and programming languages. A new branch of science called mathematical linguistics (in its narrow meaning) arose from these studies.

During the next three decades after the rise of mathematical linguistics, much effort was devoted to improve its tools for it to better correspond to facts of natural languages. At the beginning, this research stemmed from the basic ideas of Chomsky and was very close to them.

However, it soon became evident that the direct application of simple context-free grammars to the description of natural languages encounters great difficulties. Under the pressure of purely linguistic facts and with the aim to better accommodate the formal tools to natural languages, Chomsky proposed the so-calledtransformational grammars. They were mainly English-oriented and explained how to construct an interrogative or negative sentence from the corresponding affirmative one, how to transform the sentence in active voice to its passive voice equivalent, etc.

For example, an interrogative sentence such as Does John see Mary? does not allow a nested representation as the one shown on page 37 since the two words does and see obviously form a single entity to which the word John does not belong. Chomsky’s proposal for the description of its structure consisted in

(a) description of the structure of some “normal” sentence that does permit the nested representation plus

(b) description of a process of obtaining the sentence in question from such a “normal” sentence by its transformation.

Namely, to construct the interrogative sentence from a “normal” sentence “John sees Mary.”, it is necessary

(1) to replace the period with the question mark (*John sees Mary?),

(2) to transform the personal verb form see into a word combination does see (*John does see Mary?), and finally

(3) to move the word does to the beginning of the sentence (Does John see Mary?), the latter operation leading to the “violation” of the nested structure.

This is shown in the following figure:

                          S
                         
Nested: John N does see V Mary N VP ?

 

                       
                       
Not nested: Does John N see V Mary N ?

 

A transformational grammar is a set of rules for such insertions, permutations, movements, and corresponding grammatical changes. Such a set of transformational rules functions like a program. It takes as its input a string constructed according to some context-free grammar and produces a transformed string.

The application of transformational grammars to various phenomena of natural languages proved to be rather complicated. The theory has lost its mathematical elegance, though it did not acquire much of additional explanatory capacity.

THE LINGUISTIC RESEARCH AFTER CHOMSKY:
VALENCIES AND INTERPRETATION

After the introduction of the Chomskian transformations, many conceptions of language well known in general linguistics still stayed unclear. In the 1980’s, several grammatical theories different from Chomsky’s one were developed within the same phrase-structure mainstream. Nearly all of them were based on theCFGs, but used different methods for description of some linguistic facts.

One very important linguistic idea had been suggested already by Chomsky and adopted by the newer theories. It is the subcategorization of verbs according to their ability to accept specific sets of complements. These complements are also called actants, or valency fillers, which we will use interchangeably. We also will informally use the term valency for valency filler, though valency is a link, whereas a valency filler is a linked word or a word group.

The term valency is also used in chemistry, and this is not by accident. The point is that each specific verb has its own standard set of actants (usually nouns). Within a sentence, the actants are usually located close to the predicative verb and are related with it semantically. For example, the Spanish verb dar has three actants reflecting (1) donator (who gives?), (2) donation (what is given?) and (3) receptor (to whom is given?).

In texts, the valencies are given in specific ways depending on the verb, e.g., with a specific word order and/or a specific preposition for each valency. All three actants of the verb dar can be seen in the sentence Juan (1) dio muchas flores (2) a Elena (3). The last two actants and their position in a sentence after the verb dar can be expressed with the pattern:

dar <donation> a <receptor>

The description given above reflects linguistic phenomena including both syntactic and semantic aspects of valencies. In particular, the names <donator>, <donation>, and <receptor> reflect valencies in their semantic aspect. As to the generative grammar approach, it operates only with constituents and related grammar categories. Under this approach, the pattern called subcategorization frame has the form:

dar N1 a N2,

where N1 and N2 stand for noun phrases, without exposure of their semantic roles. Thus, these phrases are not distinguishable semantically, they only can be given different syntactic interpretations: N1 is a direct complement and N2 is an indirect complement.

We have induced only one of the possible subcategorization frames for the verb dar. To reflect the structure of the sentence Juan (1) dio a Elena (3) muchas flores (2), with the same semantic valencies given in a different order, we are compelled to introduce another pattern:

dar a <receptor> <donation>

with the corresponding subcategorization frame

dar a N1 N2.

Direct and indirect complements swap over, while their semantic roles stay the same, bit it is not clear in such a subcategorization frame.

Categorization and subcategorization are kinds of classification. Any consistent classification implies separation of entities to several non-intersecting groups. However, in the case under our study, the verb dar should be considered belonging to two different subcategories. Or else two verbs dar should be introduced, with equal meanings and equal semantic valency sets, but with different subcategorization frames. In fact, the situation in languages with the free word order is even more complicated. Indeed, the verb dar can have their donation and receptor actants staying before the subject, like in the sentence A Elena (3) le dio Juan(1) muchas flores (2). Such an order requires even more subcategorization frames obligatorily including the subject of the sentence, i.e. the first valency or the verb, with the role of donator.

The actants are used with verbs more frequently than the so-called circonstants. The circonstants are expressed by adverbs or, similarly to actants, by prepositional groups, i.e., through a combination of a preposition and (usually) a noun. However, the way they are expressed in text does not usually depend on a specific verb. Thus, in the first approximation, the difference between actants and circonstants can be roughly summarized as follows.

· In the syntactic aspect, actants are expressed peculiarly depending on the specific verb, whereas circonstants do not depend on the specific verb in their form, and

· In the semantic aspect, actants are obligatory participants of the situation described by the verb, while circonstants are not.

Only one, obligatory and usually the most important, participant of the situation is expressed by many languages in a quite standard form, namely the subject of the sentence. In Spanish, English, and several other languages (but not in all of them!), it usually precedes the syntactic predicate of the sentence and is represented with a noun without any preposition. Since the subject is expressed in the same manner with all verbs, it is not specified explicitly in the subcategorization frames. However, it is efficient only for languages with strict word order.

As we could see above, the semantic interpretation of different phrases within a sentence cannot be given in the frame of the purely generative approach. It can only distinguish which noun phrase within a sentence is subject, or direct complement, or indirect complement, etc. In deep semantic interpretation (“understanding”), additional theoretical means were needed, and they were first found out of the generative approach. In late 60s, Charles Fillmore [13] has introduced semantic valencies under the name of semantic cases. Each verb has its own set of semantic cases, and the whole set of verbs in any language supposedly has a finite and rather limited inventory of all possible semantic cases. Just among them, we can see semantic cases of donator, donation, and receptor sufficient for interpretation of the verb dar. To “understand” any verb deeper, some rules connecting subcategorization frames and semantic cases had been introduced.






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