GATE CSE 2015 Set 3 | Question: 16

Question

Among simple LR (SLR), canonical LR, and look-ahead LR (LALR), which of the following pairs identify the method that is very easy to implement and the method that is the most powerful, in that order?

• A. SLR, LALR
• B. Canonical LR, LALR
• C. SLR, canonical LR
• D. LALR, canonical LR

Answer 1

Answer is C.

SLR is the simplest to implement and Canonical LR is the most powerful.

http://en.wikipedia.org/wiki/LALR_parser_generator

Comments

From Ullman, Compilers [1986]

From Green Tiger Compiler book by Andrew Appel

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@HitechGa bro do have any diagram for where operator precedence grammar lies in the diagram.

Answer 2

Answer:B according to ace academy solutions

Anyone with the explanation why its not A?

Comments

http://en.wikipedia.org/wiki/LALR_parser_generator

C is right.

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PLEASE REFER THE DIAGRAM GIVEN BELOW

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There are some LL(1) grammars which are not LALR(1).

http://stackoverflow.com/questions/6487588/example-for-ll1-grammer-which-is-not-lalr

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is LL(1) outside LALR(1) box correct? I thought whatever LL(1) can parse can be parsed by LALR(1)

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@Piyush, This can't be parsed by LALR but LL(1) can.

S --> ( x
S --> E ]
S --> F )

X --> E )
X --> F ]

E --> A
F --> A

A --> .