Natural language processing began with a twentieth century view of linguistics and more specifically grammar. It is no longer believed by many linguists today that natural language forms a tree. That does not mean that parsing is invalid or that a tree structure can't be employed at all. What it means is that the way teachers used to force students to fit strict rules was not and may never be followed by people at parties, bloggers online, writers of technical documents, poets, or Pulitzer Prize winners.
Language is not only dynamic in terms of the order and interrelationships between linguistic elements, but also across geographies and across time. That is why NLP is so difficult to comprehend and program. One must discard rules.
There are times when what is in dictionaries as a noun describes an action like a verb or modifies another noun, therefore acting as an adjective. There are times when what is in dictionaries as a verb describes a type of object like a noun or modifies another verb, therefore acting like an adverb. If done frequently enough, the other part of speech will begin to appear in dictionaries, which must ultimately adapt to changing language. All attempts to pin down language in time have failed throughout history, and all attempts to develop relational mappings based on word proximity and order have failed.
In summary, language is amorphous, colloquial, and in constant flux based on trends in media, social intercourse, and technology.
The flexible and comprehensive (and therefore correct) way to represent sound and text is a sequence of linguistic elements. The elements may be shorter than a word, like "re-" or "-ing", or they may be longer than a word, such as all word compositions before they become hyphenated and then single words like, "be hinde" --> "be-hind" --> "behind". A more recent example is "data set" --> "data-set" --> "dataset".
Now consider data structures to support your sentence.
I just read about Parse Tree for parsing a sentence as an Input for NLP Task.
Parse Tree could be thought of as an adjective modifying a noun, but you capitalized it because you think of "Parse Tree" as a linguistic element cognitively, whether or not you are cognoscente of that coupling, otherwise the sentence would have been.
I just read about a tree for parsing a sentence as an Input for NLP Task.
NLP has become a single entity cognitively as well, thus the popularity of the acronym, which no longer means processing that happens to work on language which happens to be natural. If those ideas were separate, then the obviousness that a tree does not really model the nature of the sentence we are using as an example. First of all, tree nodes can only have one parent and the word, "Input," relates to both the task and the sentence. So does the word, "Read." In fact, a directed graph representing the relationships between linguistic elements for this sentence will have multiple incoming edges for several vertices and there will also be cycles, so it is not even acyclic.
Parsing is still one way to develop a directed graph representation of the phrase and begin to develop a semantic mapping of the cognitive content expressed. It is not the only way and is not likely the way the human brain does it. A tree may be involved in processing, but probably a spanning tree across the directed graph. Again, that's probably not the way the human brain does it.
Another aspect of NLP to consider is that, if a linguistic expert is required to validate any part of the process, it is not artificial intelligence. Such would be semi-automated natural language processing, which would not be of much commercial or even research value.
There is little doubt that the language capabilities of the human brain use structures of the same type. People who learn two or three languages have an easier time learning the next one. This is a strong indication that language processing, cognition, and the formulation of responses are language independent. Thus a single type of phrase to semantic conversion occurs using similar structure of linguistic elements and similar structures of cognition. There may not be complete language independent overlap, but at least partial. We see this as some pairs of bilingual people will switch between languages in the same phrase with grace, as if it was easier to express something with two languages than it would have been if one was chosen.
Surely, a phrase has more than one structure to represent it. The likelihood that a person hearing a phrase and repeating it back has the same understanding of the phrase as the original speaker or the same association strengths and semantic relationships either. The culture of the speaker and the listener or the writer and the reader depends on complex and extensive conceptual consensus or at least near consensus for comprehension to result during dialog.