زبان و زبانشناسی

Generative Grammar” was firstly introduced by Noam Chomsky, an American mathematician, politician and linguist. Chomsky tried to compare languages with mathematics. He said language rules are similar to algebra expressions.  

For instance, “x + y = z” can make different results. We give x and y the value of any whole number , then that algebra expression can “generate” an endless set of values .
Chomsky said language rules work somehow the same. Knowing finite set of rules, we may “generate” an infinite set of sentences.
That is why he called his grammar “Generative Grammar”.

Ambiguous structures and synonymous sentences were two subjects generative grammar tried to argue about syntactically.
“Mary hit the boy with a stick.”
 
This sentence has two underlying interpretations.
1. Mary had a stick and she hit the boy with it.
2. Mary hit a boy who happened to be carrying a stick.

A grammar should be able to explain this event which is called structural ambiguity.
 
“John broke the glass.” and “the glass was broken by John.” are considered to be synonymous or at least very closely related.
A grammar should be able to explain this event too.

Generative grammar proposed two levels for Language. One is an underlying level which is called “Deep Structure”. Deep structure is an abstract level of language where we have language representation before production. “Surface structure” is the term used for the other level of language. At this level we have actual oral representation of language production.

Having these considerations, generative grammar is able to explain both structural Ambiguity and Synonymous sentences.
We can discuss that in ambiguous sentences we are facing one Surface Structure (one utterance) and two different deep structures (two interpretations).
In synonymous sentences the case is the other way round. That is, two Surface structures (two utterances) and one deep structure (one interpretation).

Generative Grammar tried to formulate language utterances.
It used some symbols to achieve this goal.
* “ungrammatical sentences”
→ “Consists of” or “rewrites as”
( ) “optional constituent”
{ } “one and only one of these constituents must be selected”

The grammar proposes some rules known as phrase structure rules or simply P. S. rules. Here we introduce some of these rules.
S → NP VP
NP→ {(Art) (Adj) N, Pro, PN}
VP → V (NP) (PP) (Adv)
PP → Prep NP

While “S” stands for a sentence
“N” for a noun
“V” for a verb
“Art” for an article
“NP” for a noun phrase
“VP” for a verb phrase

This way of formulating sentences was firstly used by early structuralists putting sentences in square brackets and then bracketing changed into diagrams, known as tree diagrams.