grammar

A grammar is a structured way of explciityl capturing the normal implicit rules of natural language or defining the normative rules of an artificial one. Grammars are often expressed in terms of grammar rules that map non-terminal symbols (such as SENTANCE or NOUN_PHRASE) expressing phrases or logical groups of words, terminal symbols often single words (such as 'dog'), and grammar rules that exress how non-terminal symbols expand . In natural language processing, grammars are often used to turn an input sentance or text into a parse tree.