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.