Context-Free Grammer

Definition − A context-free grammar (CFG) consisting of a finite set of grammar rules is a quadruple (N, T, P, S) where

--N is a set of non-terminal symbols.

--T is a set of terminals where N ∩ T = NULL.

--P is a set of rules, P: N → (N ∪ T)*, i.e., the left-hand side of the production rule P does have any right context or left context.

--S is the start symbol.

Example:
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The grammar ({A}, {a, b, c}, P, A), P : A → aA, A → abc.
The grammar ({S, a, b}, {a, b}, P, S), P: S → aSa, S → bSb, S → ε
The grammar ({S, F}, {0, 1}, P, S), P: S → 00S | 11F, F → 00F | ε