Consider the grammar below A → BB B → bB | c B → c

Consider the grammar below

A → BB

B → bB | c

B → c

Answer: A. Both LL(1) and LR(1)Grammar: A → B B , B → bB | c Compute FIRST sets: FIRST(B) = {b, c}. There is no ε-production for B. LL(1) check: The two alternatives for B start with…

  1. A.

    Both LL(1) and LR(1)

  2. B.

    Neither LL(1) nor LR(1)

  3. C.

    LR(1)

  4. D.

    LL(1)

Attempted by 31 students.

Show answer & explanation

Correct answer: A

Grammar: A → B B , B → bB | c

  • Compute FIRST sets:

    FIRST(B) = {b, c}. There is no ε-production for B.

  • LL(1) check:

    The two alternatives for B start with different terminals (b and c), so their FIRST sets are disjoint. A has a single production A → B B, so there are no competing productions for A.

  • Conclusion about LL(1):

    Because alternatives for each nonterminal have disjoint FIRST sets and no ε is involved, the grammar is LL(1).

  • LR(1) check:

    LR(1) parsers are more general than LL(1); any LL(1) grammar will have LR(1) item sets with no shift/reduce or reduce/reduce conflicts. Therefore this grammar is also LR(1).

Final answer: the grammar is both LL(1) and LR(1).

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