Formal Grammars of English

Grammar is defined as set of rules and conventions that govern any language[1]
Furthermore, it is used to determine whether the given sentence is proper sentence; follows the rules of language or not[2]
We use grammar and parsing to know the meaning of the sentence[2]

Constituency

It is a word or group of words in a sentence that acts like a noun
- Example You could say, ''I met Ramesh'' . In this sentence noun is ''Ramesh'', but if you replace it with a group of words(phrase) and say, ''I met your brother''. Now here ''your brother'' is a phrase(a group of words without a finite verb), and it functions as a noun in the sentence
In other words, noun phrase is group of words that contains at least one noun.
- Possible Evidences to group Words
One way is that they can all appear in similar syntactic environments such as noun phrases can occur before verbs
Another way can be from preposed(beginning of sentence) or ** postposed(end of sentence)** constructions:
- Example prepositional phrase on December eighteenth can be written on different positions of sentence:
- - On December eighteenth, I’d like to fly from Atlanta to Denver
- - I’d like to fly on December eighteenth from Atlanta to Denver
- - I’d like to fly from Atlanta to Denver on December eighteenth