Question

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

x → c.x, c/d    x → c.x, $ 

x → .cx, c/d   x → .cx, $

x→ .d, c/d   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 a heads 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 go to on c will lead to two different sets

(A) 1 only

(B) 2 only

(C) 1 and 4 only

(D) 1, 2, 3 and 4

Answer 1

Correct option is (D) 1, 2, 3 and 4

1. Merging of two states depends on core part (production rule with dot operator), not on look a heads. 

2. The two states are not containing Reduce item ,So after merging, the merged state can not contain any S-R conflict 

3. As there is no Reduce item in any of the state, so can’t have R-R conflict. 

4. Merging of stats does not depend on further go to on any terminal. So all statements are false.