The meaning text theory: dependency trees
Another important feature of the MTT is the use of its dependency trees, for description of syntactic links between words in a sentence. Just the set of these links forms the representation of a sentence at the syntactic level within this approach.
FIGURE II.2. Example of a dependency tree. |
For example, the Spanish sentence La estudiante mexicana canta una canción can be represented by the dependency tree shown in Figure II.2. One can see that the dependency tree significantly differs from the constituency tree for the same sentence (cf. Figure II.1).
Up to the present, the proper description of the word order and word agreement in many languages including Spanish can be accomplished easier by means of the MTT. Moreover, it was shown that in many languages there exist disrupt and non-projective constructions, which cannot be represented through constituency trees or nested structures, but dependency trees can represent them easily.
In fact, dependency trees appeared as an object of linguistic research in the works of Lucien Tesnière, in 1950’s. Even earlier, dependencies between words were informally used in descriptions of various languages, including Spanish. However, just the MTT has given strict definition to dependency trees. The dependency links were classified for surface and deep syntactic levels separately. They were also theoretically isolated from links of morphologic inter-word agreement so important for Spanish.
With dependency trees, descriptions of the relationships between the words constituting a sentence and of the order of these words in the sentence were separated from each other. Thus, the links between words and the order in which they appear in a sentence were proposed to be investigated apart, and relevant problems of both analysis and synthesis are solved now separately.
Hence, the MTT in its syntactic aspect can be called dependency approach, as contrasted to the constituency approach overviewed above. In the dependency approach, there is no problem for representing the structure of English interrogative sentences (cf. page 39). Thus, there is no necessity in the transformations of Chomskian type.
To barely characterize the MTT as a kind of dependency approach is to extremely simplify the whole picture. Nevertheless, this book presents the information permitting to conceive other aspects of the MTT.
The meaning text theory: semantic links
The dependency approach is not exclusively syntactic. The links between wordforms at the surface syntactic level determine links between corresponding labeled nodes at the deep syntactic level, and after some deletions, insertions, and inversions imply links in the semantic representation of the same sentence or a set of sentences. Hence, this approach facilitates the transfer from syntactic representations to a semantic one and vice versa.
According to the MTT, the correlation between syntactic and semantic links is not always straightforward. For example, some auxiliary words in a sentence (e.g., auxiliary verbs and some prepositions) are treated as surface elements and disappear at the deep syntactic level. For example, the auxiliary Spanish verbHABER in the word combination han pedido disappears from the semantic representation after having been used to determine the verb tense and mode. At the same time, some elements absent in the surface representation are deduced, or restored, from the context and thus appear explicitly at the deep syntactic level. For example, given the surface syntactic dependency tree fragment:
su hijo Juan,
the semantically conditioned element NAME is inserted at the deep syntactic level, directly ruling the personal name:
su hijo NAME Juan
Special rules of inter-level correspondence facilitate the transition to the correct semantic representation of the same fragment.
The MTT provides also the rules of transformation of some words and word combinations to other words and combinations, with the full preservation of the meaning. For example, the Spanish sentence Juan me prestó ayuda can be formally transformed to Juan me ayudó and vice versa at the deep syntactic level. Such transformations are independent of those possible on the semantic level, where mathematical logic additionally gives quite other rules of meaning-preserving operations.
We should clarify that some terms, e.g., deep structure or transformation, are by accident used in both the generative and the MTT tradition, but in completely different meanings. Later we will return to this source of confusion.
All these features will be explained in detail later. Now it is important for us only to claim that the MTT has been able to describe any natural language and any linguistic level in it.