Posts Tagged ‘Grammar’
Lexical Functional Grammar (LFG) was developed by Kaplan and Bresnan in 1980’s. As the name suggests lexicon plays a major role in LFG. It claims having computational viability and cognition. LFG competes with Government and Binding theory.
LFG has two levels of processing. In the first level, phrase structure rules (CFGs) are used to get a tree structure. This tree structure, known as constituent structure or C structure, captures the linear and hierarchical relationships. Thereafter functional structure of F-structure is obtained by unifying feature bundles.
There are similarities between LFG and ATN. The CFG rules that generate C-structure are similar to the unaugmented part of ATN. The functional description of LFG are similar to the augmentation in ATN. So LFG grammars are as powerful as ATN grammars.
LFG employs double shafted arrow mechanism for dealing with long distance dependencies. The double shafted mechanism is less natural and less intuitive. LFG chose direct linking of functionally dependent constituents. . Also it uses single operation of unification thereby making the grammar easy to write. Unification, on the other hand, is a costly operation. Unification results in large number of feature structures built and then rejected.
Script grammar is a grammar at the level of scripts. It is a unique characteristic of Indian languages. Unlike western languages, Indian scripts are directly based on phonetics. The units of orthography are essentially C*V syllables where C denotes consonant sound and V denotes vowel sound. C*V syllables are known as aksharas, the atomic units of writing. There are more than 5000 aksharas covering the words of all the major Indian languages. Script Grammars define the manner in which a script of a given (Indian) language is to be written.
The script grammar is a grammar of scripts. It accepts only valid aksharas. This is to ensure that invalid sequences do not occur in any language.
Introduction To Universal Grammar
Universal grammar is the brainchild of Noam Chomsky. In contrast to taxonomic approach of traditional grammar, universal grammar adopts cognitive approach. Cognition is the study of processes by means of which what human beings get to know the world. Human beings have tacit (i.e. Subconscious) knowledge of grammar. That is humans know how to form and interpret expressions in their native languages. they know but they may not explain how they get this ability. This is because they have no conscious awareness of the processes involved.
Competence and Performance
Chomsky says that native speakers have grammatical competence (i.e. Tacit knowledge) in their native language. Chomsky made difference between competence and performance. According to him while competence is knowledge of language performance is the actual use of language in concrete situations. Universal grammar is concerned with competence in that it tells what someone should know to have competence in a language. Note that performance is properly studied in psycholinguistics. Theoretically Universal Grammar (UG) generalises from the grammars of particular I-languages (i.e. Internalised linguistic system) to the grammars of all possible natural I- languages.
Universal Grammar Theory
Universal grammar is a theory of knolwedge. It is not a theory of behaviour. It mainly concerns with the internal structure of human mind. Universal grammar theory holds that the speaker knows a set of principles that apply to all languages, and parameters that vary from one language to another. Universal grammar theory is making precise statements about properties of the mind based on specific evidence. It important to note that the theory attempts to integrate grammar, mind and langauge at very moment.
Chomsky’s Questions on Linguistics
Following questions of Chomsky summarizes the aims of linguistics.
1. What constitutes knowledge of language? The linguists duty is to describe what people know about language.
2. How is such knowledge acquired? A linguist has to discover how people acquire this knowledge.
3. How is such knowledge put to use? The linguists have to see how people use the language knowledge acquired.
Sometimes there is a fourth question also.
4. What are the physical mechanisms that serve as the material basis for this system of knowledge and for the use of this knowledge? There must be some physical correlate to this mental knowledge. That is there should be a link between mind and brain.
I-Language and E-Language
Chomsky distinguishes Externalized (E-) language from Internalized (I-) language. E language linguistics aims to collect samples of language and then to describe their properties. The linguist’s task is to bring order to the set of external facts that make up the language. The resulting grammar is described in terms of properties of such data through ‘structures’ or ‘patterns’. I-language linguists on the other hand is concerned with what a speaker knows about a language and where this language knowledge comes from. I-language treats language as an internal property of the human mind rather than something external. Chomsky’s theories fall within the I-language tradition and aim at exploring the mind rather than environment. I-language theory claims that establishing knowledge itself logically precedes studying how people acquire and use that knowledge. Chomsky introduced the term pragmatic competence: knowledge of how language is related to the situation in which it is used. Knowledge of language use is different from knowledge of language itself. So it may be possible to have grammatical competence without pragmatic competence.
Grammar studies the way in which words/morphemes join to form meaningful sentences. Grammar is a set of constraints on the possible sequences of symbols expressed as rules or principles. Syntax is the basic ingredient of grammar. Grammar tells us the difference between sets of sentences.
There are five fundamental units of grammatical structure: morpheme, word, phrase, clause, and sentence. Morpheme is the lowest unit. Morphemes joined to form word. Phrase and clause are group of words. While phrase does not have subject and predicate, clause does have its own subject and predicate. In a sentence, Joe sings, Joe is subject and sings is predicate. Sentence is also a group of words that convey some meaning.
Note that what is described above is called traditional grammar. Subject, predicate, etc are called grammatical functions. Parts-of-speech such as verb, noun, adjective are called grammatical categories.
Computational grammars are those that are meant for Natural Language processing. They should be detailed, precise and exhaustive. They should be descriptive grammars so that computers can correctly interpret and apply them.
For Further Study
1. Pushpinder Syal, D.V.Jindal, An Inroduction to Linguistics, Second Edition, PHI, 2009.
2. Andrew Radford, Minimalist Sytax, Cambridge Universtiy Press, 2004.