UGC NET CSE | December 2012 | Part 2 | Question: 27

Question

Which of the following is true while converting CFG to an LL(1) grammar?

• A. Removing left recursion alone
• B. Factoring the grammar alone
• C. Removing left recursion and factoring the grammar
• D. None of the above

Answer 1

Answer :  while converting CFG to LL(I) grammar we have to see 

Remove left recursion 
Factoring grammar 

Reference : information about Conversion from CFG to LL(1) Grammar  is Here

It must be noted that even after the above 2 steps there is no guarantee that we get an LL(1) grammar as for that our grammar must be unambiguous as well. See one related question here. 

Comments

so what is ans here ?

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C . Both of above

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so what about ambiguous grammar ?

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there is nothing asked about ambiguous or unambiguous here .so i did not consider them

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then after removing both grammar may be still ambiguous .So it will not LL(1).Hence d is correct option.

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For GATE answer is D.

For NET it is C :)

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thanks i belongs to GATE .

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both question has different options merging them is not a good idea .

you are answering this question by looking at these options .but in that case option c is the appropriate choice.

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@shekhar you are correct. I'll restore. Missed the "suffices".

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yes in GATE the word "suffices" makes difference https://gateoverflow.in/906/gate2003-16

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sir left factoring convert non-deterministic to deterministic and a deterministic is always unambigious I think so why not option C is sufficient ?

Answer 2

Option C will be right option for it.

Bcz when we will convert any CFG such grammar do not have the propert of the Left recrsion along with there does not exist any non-deterministic grammar for it.

So option C will be right option for it.