Alternative Definition
Another way to define Chomsky normal form (e.g., Hopcroft and Ullman 1978,and Hopcroft et al. 2006) is:
A formal grammar is in Chomsky reduced form if all of its production rules are of the form:
- or
where, and are nonterminal symbols, and α is a terminal symbol. When using this definition, or may be the start symbol. Only those context-free grammars which do not generate the empty string can be transformed into Chomsky reduced form.
Read more about this topic: Chomsky Normal Form
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