2. Phrase Rules Structure
• Phrase-structure rules are a way to describe a given language
• S=> NP VP ; NP => Det + N1 ; N1 => AP N1 PP
• The first rule reads: An S (sentence) consists of an NP (noun phrase)
followed by a VP (verb phrase). The second rule reads: A noun phrase
consists of a Det (determiner) followed by an N (noun). Some further
categories are listed here: AP (adjective phrase), AdvP (adverb phrase), PP
(prepositional phrase), etc. Applying the phrase structure rules in a neutral
manner, it is possible to generate many proper sentences of English. But it
is also quite possible that the rules generate syntactically correct but
semantically nonsensical sentences. The following example sentence is
notorious in this regard, since it is complete nonsense, even though it is
syntactically correct:
• Colorless green ideas sleep furiously
• This sentence was constructed by Noam Chomsky as an illustration that
phrase structure rules are capable of generating
3. • syntactically correct but semantically incorrect sentences. Phrase structure
rules break sentences down into their constituent parts. These constituents
are often represented as tree structures. The tree for Chomsky's famous
sentence can be rendered as follows:
• A constituent is any word or combination of words that is dominated by a
single node. Thus each individual word is a constituent. Further, the subject
NP Colorless green ideas, the minor NP green ideas, and the VP sleep
furiously are constituents. Phrase structure rules and the tree structures
that are associated with them are a form of immediate constituent analysis.
4. Transformational Grammar
• In linguistics, a transformational grammar or transformational-generative
grammar (TGG) is a generative grammar, especially of a natural
language, that has been developed in the Chomskyan tradition of phrase
structure grammars (as opposed to dependency grammars).
Additionally, transformational grammar is the tradition that gives rise to
specific transformational grammars.
• In 1957, Noam Chomsky published Syntactic Structures, in which he
developed the idea that each sentence in a language has two levels of
representation — a deep structure and a surface structure. The deep
structure represented the core semantic relations of a sentence, and was
mapped on to the surface structure (which followed the phonological
form of the sentence very closely) via transformations. Chomsky believed
there are considerable similarities between languages' deep
structures, and that these structures reveal properties, common to all
languages that surface structures conceal. However, this may not have
been the central motivation for introducing deep structure.
5. • Transformations had been proposed prior to the development of deep
structure as a means of increasing the mathematical and descriptive
power of context-free grammars. Similarly, deep structure was devised
largely for technical reasons relating to early semantic theory.
• Generative grammar refers to a particular approach to the study of syntax.
A generative grammar of a language attempts to give a set of rules that
will correctly predict which combinations of words will form grammatical
sentences. In most approaches to generative grammar, the rules will also
predict the morphology of a sentence.
• Generative grammar originates in the work of Noam Chomsky, beginning
in the late 1950s. Early versions of Chomsky's theory were called
transformational grammar, and this term is still used as a collective term
that includes his subsequent theories. There are a number of competing
versions of generative grammar currently practiced within linguistics.
Most versions of generative grammar characterize sentences as either
grammatically correct (also known as well formed) or not. The rules of a
generative grammar typically function as an algorithm to predict
grammaticality as a discrete (yes-or-no) result.
6. morphophonemic
• Morphophonology (also morphophonemics, morphonology) is a branch of
linguistics which studies the interaction between morphological and
phonological or phonetic processes. Its chief focus is the sound changes that
take place in morphemes (minimal meaningful units) when they combine to
form words.
• Morphophonological analysis often involves an attempt to give a series of
formal rules that successfully predict the regular sound changes occurring in
the morphemes of a given language. Such a series of rules converts a
theoretical underlying representation into a surface form that is actually
heard. The units of which the underlying representations of morphemes are
composed are sometimes called morphophonemes. The surface form
produced by the morphophonological rules may consist of phonemes (which
are then subject to ordinary phonological rules to produce speech sounds or
phones), or else the morphophonological analysis may bypass the phoneme
stage and produce the phones itself.
7. • When morphemes combine, they influence each other's sound structure
(whether analyzed at a phonetic or phonemic level), resulting in different
variant pronunciations for the same morpheme. Morphophonology
attempts to analyze these processes. A language's morphophonological
structure is generally described with a series of rules which, ideally, can
predict every morphophonological alternation that takes place in the
language.
• An example of a morphophonological alternation in English is provided by
the plural morpheme, written as "-s" or "-es". Its pronunciation alternates
between [s], [z], and [ɪz], as in cats, dogs, and horses respectively. A
purely phonological analysis would likely assign to these three endings the
phonemic representations /s/, /z/, /ɪz/. On a morphophonological
level, however, they may all be considered to be forms of the underlying
object //z//, which is a morphophonemic. The different forms it takes are
dependent on the segment at the end of the morpheme to which it
attaches – these dependencies are described by morphophonological
rules. (The behaviour of the English past tense ending "-ed" is similar – it
can be pronounced [t], [d] or [ɪd], as in hoped, bobbed and added.)
