Minimization of DFA using Myhill -Nerode Theorem (Table Filling Method)

 

Minimization of DFA (Table Filling Method)

Handwritten Notes- Click Here

                                          

State

Input 0

Input 1

A

B

F

B

G

C

C

A

C

E

H

F

F

C

G

G

G

E

H

G

C

Final State = {C}

Non-Final States = {A, B, E, F, G, H}


Step 1: Construct the State Pair Table

A final state and a non-final state cannot be equivalent.

                 Final State + Non-Final State → Mark(X)


B

Unmarked


C

X

X


E

Unmarked

Unmarked

X


F

Unmarked

Unmarked

X

Unmarked


G

Unmarked

Unmarked

X

Unmarked

Unmarked


H

Unmarked

Unmarked

X

Unmarked

Unmarked

Unmarked

State

A

B

C

E

F

G



Iteration 1

Check all the remaining unmarked pairs.

Pair

0

1

Result

(A,B)

(B,G)

(F,C)

X

(A,E)

(B,H)

(F,F)

Blank

(A,F)

(B,C)

(F,G)

X

(A,G)

(B,G)

(F,E)

Blank

(A,H)

(B,G)

(F,C)

X

(B,E)

(G,H)

(C,F)

X

(B,F)

(G,C)

(C,G)

X

(B,G)

(G,G)

(C,E)

X

(B,H)

(G,G)

(C,C)

Blank

(E,F)

(H,C)

(F,G)

X

(E,G)

(H,G)

(F,E)

X

(E,H)

(H,G)

(F,C)

X

(F,G)

(C,G)

(G,E)

X

(F,H)

(C,G)

(G,C)

X

(G,H)

(G,G)

(E,C)

X

Blank pairs:
(A,E), (A,G), (B,H)
 
 After Iteration 1, the state-pair table

B

X


C

X

X


E

Unmarked

X

X


F

X

X

X

X


G

Unmarked

X

X

X

X


H

X

Unmarked

X

X

X

X

State

A

B

C

E

F

G




Iteration 2

Recheck only the blank pairs from Iteration 1.


Pair

0

1

Result

(A,E)

(B,H)

(F,F)

Blank

(A,G)

(B,G)

(F,E)

X

(B,H)

(G,G)

(C,C)

Blank


Blank pairs:
(A,E), (B,H)

After Iteration 2, the state-pair table

B

X


C

X

X


E

Unmarked

X

X


F

X

X

X

X


G

X

X

X

X

X


H

X

Unmarked

X

X

X

X

State

A

B

C

E

F

G



Iteration 3

Recheck only the blank pairs from Iteration 2.


Pair

0

1

Result

(A,E)

(B,H)

(F,F)

Blank

(B,H)

(G,G)

(C,C)

Blank


No new pair is marked.

Therefore, the unmarked pairs are equivalent states.

Equivalent States
A ≡ E

B ≡ H

Transition Table of Minimized DFA

State

0

1

A

B

F

B

G

C

C

A

C

F

C

G

G

G

A

Number of states before minimization = 7

Number of states after minimization = 5


Video Explanation



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