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1 vote
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An unambiguous grammar has same leftmost and rightmost derivation.

True or False

and how??
in Compiler Design
edited by 108 views
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Ambiguity has no relation with left most and right most derivation.It is true.Every grammer if it has some string then it will have both left and right deravation

1 Answer

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"An unambiguous grammar has same leftmost and rightmost derivation"

This statement is false, let me take an example, suppose given gammer is (which is certainly unambiguous)

S -> AB
A -> a
B -> b

Suppose our input string is ab

Left Most Derivation
S -> AB -> aB -> ab

Right Most Derivation
S -> AB -> Ab -> ab

Notice Left Most derivation and Right most derivation are not same, still gammer is unambiguous.

Here is the Derivation Tree


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