GATE CSE 2017 Set 1 | Question: 17

Question

Consider the following grammar:

• $P\rightarrow xQRS$
• $Q\rightarrow yz\mid z$
• $R\rightarrow w\mid \varepsilon$
• $S\rightarrow y$

What is FOLLOW($Q$)?

• A. $\left \{ R \right \}$              
• B. $\left \{ w \right \}$                
• C. $\left \{ w,y \right \}$                   
• D. $\left \{ w,\$ \right \}$

Answer 1

In the production: P → xQRS,
FOLLOW (Q) = FIRST (R)
FIRST (R) = {w, ϵ} >br> Since FIRST (R) = {ϵ}, so FOLLOW (Q) → {w} ∪ FIRST(S)
FIRST(S) = {y}
So, FOLLOW (Q) = {w, y}

Answer 2

c is correct

Answer 3

Ans option d

Comments

answer d is not correct because for Follow of Q we have to find first of R and there is epsilon move in first of R so by putting epsilon in P now we have to find first of S hence option C

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so plz correct ur answer