A canonical set of items is given below

$$\eqalign{ & S \to L. > R \cr & Q \to R. \cr} $$

On input symbol < the set has

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

$$\eqalign{ & X \to c.X,\,c/d\,\,\,\,\,\,\,\,X \to c.X,\$ \cr & X \to .cX,c/d\,\,\,\,\,\,\,\,X \to .cX,\$ \cr & X \to .d,c/d\,\,\,\,\,\,\,\,\,\,\,X \to .d,\$ \cr} $$

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.

The grammar $$S \to aSa\,|\,\,bS\,|\,\,c$$ is

An LALR(1) parser for a grammar G can have shift-reduce (S-R) conflicts if and only if