Production (computer Science)
A production or production rule in computer science is a rewrite rule specifying a symbol substitution that can be recursively performed to generate new symbol sequences. A finite set of productions is the main component in the specification of a formal grammar (specifically a generative grammar). The other components are a finite set of nonterminal symbols, a finite set (known as an alphabet) of terminal symbols that is disjoint from and a distinguished symbol that is the start symbol.
In an unrestricted grammar, a production is of the form where and are arbitrary strings of terminals and nonterminals however may not be the empty string. If is the empty string, this is denoted by the symbol, or (rather than leave the right-hand side blank). So productions are of the form:
Where is the Kleene plus operator, is the Kleene star operator, and denotes set union.
The other types of formal grammar in the Chomsky hierarchy impose additional restrictions on what constitutes a production. Notably in a context-free grammar, the left-hand side of a production must be a single nonterminal symbol. So productions are of the form:
Read more about Production (computer Science): Grammar Generation, See Also
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