In the correct grammar of above question, what is the length of the derivation…
2006
In the correct grammar of above question, what is the length of the derivation (number of steps starring from S) to generate the string albm with l ≠ m?
- A.
max(l,m) + 2
- B.
l + m + 2
- C.
l + m + 3
- D.
max(l, m) + 3
Attempted by 8 students.
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Correct answer: A
The derivation length to generate the string a^l b^m with l ≠ m starts from S and involves producing each 'a' and 'b' through grammar rules. Each production step contributes to the total length. Since l ≠ m, both a's and b's must be generated separately or through distinct paths, requiring at least l + m steps for the symbols plus additional steps to transition between rules. The correct derivation length is l + m + 2, which accounts for generating all a's and b's and the necessary rule applications. Therefore, option B (l + m + 2) is correct.