Question 1

Consider the following two sets of LR(1) items of an LR(1) grammar.

X -> c.X, c/d
   X -> .cX, c/d
   X -> .d, c/d
   X -> c.X, $
   X -> .cX, $
   X -> .d, $

Which of the following statements related to merging of the two sets in the corresponding LALR parser is/are FALSE?

  1. Cannot be merged since look aheads are different.
  2. Can be merged but will result in S-R conflict.
  3. Can be merged but will result in R-R conflict.
  4. Cannot be merged since goto on c will lead to two different sets.
1 only
2 only
1 and 4 only
1, 2, 3 and 4
       Compiler-Design       Parsing-and-Syntax-Directed-Graph       GATE 2013
Question 1 Explanation: 
The two sets in LR(1) items can be merged if they only differ with look aheads symbols, so statement 1 is false.
In the given LR(1) items there is not any reduce move, so after merging it will not have SR conflict and hence statement 2 and statement 3 are false.
Statement 4 is also wrong, because goto is carried on Non-Terminals symbols, not on terminal symbols, and c is a terminal symbol.
Hence all statements are false.
There is 1 question to complete.
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