Automata Unambiguous Grammar - Javatpoint.pdf - Unambiguous...

Unambiguous Grammar
A grammar can be unambiguous if the grammar does not contain ambiguity that means if it does not
contain more than one leftmost derivation or more than one rightmost derivation or more than one parse
tree for the given input string.
To convert ambiguous grammar to unambiguous grammar, we will apply the following rules:
1. If the left associative operators (+, -, *, /) are used in the production rule, then apply left recursion in the
production rule. Left recursion means that the leftmost symbol on the right side is the same as the non-
terminal on the left side. For example,
X → Xa
2. If the right associative operates(^) is used in the production rule then apply right recursion in the
production rule. Right recursion means that the rightmost symbol on the left side is the same as the non-
terminal on the right side. For example,
X → aX
Example 1:
Consider a grammar G is given as follows:
S → AB | aaB
A → a | Aa
B → b
Determine whether the grammar G is ambiguous or not. If G is ambiguous, construct an unambiguous
grammar equivalent to G.