In the classic formalization of generative grammars first proposed by Noam Chomsky in the 1950s,[ grammar G consists of the following components:
of terminal symbols that is disjoint from N.
is the Kleene star operator and ∪
denotes set union. That is, each production rule maps from one string of symbols to another, where the first string (the "head") contains an arbitrary number of symbols provided at least one of them is a nonterminal. In the case that the second string (the "body") consists solely of the empty string—i.e., that it contains no symbols at all—it may be denoted with a special notation (often Λ
, e or �
) in order to avoid confusion.
that is the start symbol, also called the sentence symbol.A grammar is formally defined as the tuple (�,Σ,�,�)
nouns (N)
adjectives (Adj)
pronouns (Pro)
numerals (Num)
verbs (V)
adverbs (Adv)
particles
prepositions, conjunctions, onomatopeia, ...