First and Follow MCQ Quiz in বাংলা - Objective Question with Answer for First and Follow - বিনামূল্যে ডাউনলোড করুন [PDF]

Follow(T’)=Follow(T)={+,),$}

3 terminals in follow of T’

Answer: Option 1

Explanation:

Hence Option 1 is correct.

Follow(X) = Follow(S) ⋃ First(Y) without ɛ

= {＄} ⋃ {y}

The correct answer is {z, x}

Explanation:

To find the Follow set of the non-terminal R in the given grammar, we will analyze the production rules.

Grammar:
1. T → Qx
2. Q → RS
3. R → y | ϵ
4. S → z | ϵ

Step 1: Identify the rules involving R

From the production Q → RS :

• R appears before S , and we need to determine what can follow R .

Step 2: Determine Follow set of R

1. Check the Follow of Q :

• From T → Qx , the Follow of Q includes x .
• Thus, Follow(Q) = {x} .

2. From Q → RS :

• The symbols that can follow R are the symbols in the Follow set of S .

Step 3: Determine Follow of S

1. Check the productions for S :

• From S → z | ϵ :
• If S produces ϵ , we also consider what follows S in Q .

2. Follow of S :

• From Q → RS :
  • The symbols that can follow S include the Follow of Q , which is x (from T ).
• Thus, Follow(S) = {x} .

Step 4: Combine results for R

Since S can produce ϵ :

• The Follow set of R will include everything in Follow(S) plus anything that follows Q .
• Therefore, the Follow set of R includes:
  • The Follow of S : x
  • The Follow of Q : Since R is at the end of Q , we include whatever follows Q .

Final Step: Conclusion

Combining all the above information, the Follow set of R is: Follow(R) = {z, x}

However, since R produces y (and indirectly through Q ), and because R is followed by S which can produce ϵ , we include z in Follow of R .

Thus, the correct answer is: 3) {z, x}

Concept:

Follow(X) is the set of terminals that can appear immediately to the right of non-terminal X in some sentential form. Rules for finding the follow (X) are given here as:

1) Follow (S) = {$}, where S is the start symbol.

2) If A → bBC is the production, where b, B and C are grammar symbols, then Follow (B) is first (C).

3) If A → bB is production then follow (B) is follow (A).

4) If A → bBC is production and first(c) contains ε, then follow (B) contains {first (C) - ε} U follow (A).

Explanation:

FIRST(B) = {r, ε}

FIRST(C) = {q, ε}

FIRST(D) = {p}

FIRST(A) = FIRST (BCD) = {r, q, p}

Concept:

Follow(X) is the set of terminals that can appear immediately to the right of non-terminal X in some sentential form. Rules for finding the follow (X) are given here as:

1) Follow (S) = {$}, where S is the start symbol.

2) If A → bBC is the production, where b, B and C are grammar symbols, then Follow (B) is first (C).

3) If A → bB is production then follow (B) is follow (A).

4) If A → bBC is production and first(c) contains ε, then follow (B) contains {first (C) - ε} U follow (A).

Explanation:

FIRST(B) = {r, ε}

FIRST(C) = {q, ε}

FIRST(D) = {p}

FIRST(A) = FIRST (BCD) = {r, q, p}

Concepts:

First of X = First of A 

A → Bb | Cd

First of B = {a, c, d, ϵ}

First of C = {c, ϵ}

If ϵ is put in A → Bb | Cd

Therefore, First of A = {b, d, a, c}

First of X = First of A = {b, d, a, c}

FIRST(X) ∩ FIRST(B) = {a, b, c, d} ∩ {a, c, d, ϵ} = {a, c, d}

The correct answer is option 4.

Concept:

First Function:
First(α) is a set of terminal symbols that begin in strings derived from α.
Rules For Calculating First Function:
Rule-01:
For a production rule X → ∈,
First(X) = { ∈ }
Rule-02:
For any terminal symbol ‘a’,
First(a) = { a }
Rule-03:
For a production rule X → Y1Y2Y3,
Calculating First(X)

• If ∈ ∉ First(Y1), then First(X) = First(Y1)
• If ∈ ∈ First(Y1), then First(X) = { First(Y1) – ∈ } ∪ First(Y2Y3)

Calculating First(Y2Y3)

• If ∈ ∉ First(Y2), then First(Y2Y3) = First(Y2)
• If ∈ ∈ First(Y2), then First(Y2Y3) = { First(Y2) – ∈ } ∪ First(Y3)

Similarly, we can make expansion for any production rule X → Y1Y2Y3…..Yn.

Example
A → abc / def / ghi
First(A) = { a , d , g }

Solution:

Consider the following grammar:

E → TE'

E' →+ TE' |ϵ 

T → FT' 

T' → ∗FT' | ϵ 

F → (E) | (id)

Hence the correct answer is {∗ , ϵ}.

T → FT'

FOLLOW(F) = FIRST(T’) 

FIRST(T’) = {*, ϵ}

put ϵ in T → FT'

T → F

Therefore FOLLOW(F) = FOLLOW(T) 

FOLLOW(T)  = FIRST(E') = { +,  ϵ }    / E → TE’

put ϵ in E → TE’

E → T

FOLLOW(T)  = FOLLOW(E) 

Therefore FOLLOW(E)  = { ), $ }

NOTE:
E is start symbol

ϵ is not a follow symbol

First( ) of S = { First ( ) of A , First( ) of  ε }

First( ) of A = { First( ) of aAb, First( ) of ba } = { a , b }

First( ) of ε = ε itself is First( ) of ε

Hence First of S = {a, b, ε}

Option 2 is the correct answer