Syntax and structure of a natural language such as English are tied with a set of specific rules, conventions, and principles which dictate how words are combined into phrases, phrases get combined into clauses, and clauses get combined into sentences. All these constituents exist together in any sentence and are related to each other in a hierarchical structure.
Let’s consider a very basic example of language structure which explains a specific example in the light of subject and predicate relationship. Consider a simple sentence:
Harry is playing football
This sentence is talking about two subjects - Harry and football. To find the subject of the sentence, it is easier to first find the verb and then find “who” or “what” around it. In the above sentence, “playing” is the verb of predicate. If you ask “Who is playing?”, the answer is "Harry" which gives the first subject, and “What is he playing?” gives us "football" as the other subject. An extensive combination of similar rules allows us to define the entities (subjects), intent (predicates), the relationship between intent and entity, etc.
Such an analysis is very useful in any NLP application since it defines some meaning of the text. In a collection of words without any relation or structure, it is very difficult to ascertain what it might be trying to convey or what it means.
We'll approach the language syntax and structure problem in 3 parts: