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Linguistics

Notes The limitations or shortcomings of the phrase structure grammar can be summarised in the following
manner :

can’t disambiguate all the ambiguities;

can’t account for all syntactical
structures;
can’t explicate all grammatical
SHORT COMINGS OF PHRASE STRUCTURE GRAMMAR relations;
can’t account for discontinuous
constituents;
can’t permute, delete or adjunct;
doesn’t fully reflect the intuitions
of a native speaker;
doesn’t always stop the generation
of ungrammatical/meaningless
sentences;
doesn’t have the precision, simplicity,
elegance, power, insight,
competence of the T-G.
would be very complex and cumbersome
and clumsy with so many constraints

29.4 Chomsky’s X-Bar Theory

In syntax, the notion of a syntactic constituent is fundamental. Words, phrases, and cluses are all
types of syntactic constituents.
Once a syntactic constituent is established, its structure can be visually depicted in a phrase structure
tree diagram. We can then start formulating phase structure rules that specify the internal structures
of various syntactic constituents.
It is at this stage the X-bar theory comes into picture. It is a rule schema that specifies what kind of
valid phrase structure rules can be formulated. It, in fact, constraints the virtually unlimited power of
phrase structure rules.
The X-bar syntax/theory is a rule schema that phrase structure rules conform to, in terms of maximal
phrasal categories, intermediate categories, and (lexical) heads (e.g. N, V, A, P).
Phrase structure rules in early transformational grammar—The first kind of generative grammar
proposed by Chomsky in 1957 was transformational (generative) grammar. In its, two basic types of
syntactic rules were proposed: these were (i) phrase structure rules, and (ii) transformational rules,
or simply transformations. The phrase structure tree is constructed out of a set of phrase structure
rules of the following kind.
1. S→NP Pred-P 2. NP→Det N
3. Pred-P→Aux VP 4. VP→V PP
5. PP→P NP
The specific words or morphemes are not inserted into the terminal nodes (the smallest, indivisible
nodes) by further lexical insertion rules of the following sort:
1. Det→this 2. Det→that
3. N→boy 4. N→girl
5. V→speak 6. P→to

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