GATE | GATE-CS-2016 (Set 2) | Question 55

Which one of the following grammars is free from left recursion?

(A) A
(B) B
(C) C
(D) D

Answer: (B)
Explanation: Grammar A has direct left recursion because of the production rule: A->Aa.
Grammar C has indirect left recursion because of the production rules:S-> Aa and A->Sc
Grammar D has indirect left recursion because of production rules : A-> Bd and B-> Ae
Grammar B doesn’t have any left recursion (neither direct nor indirect).

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