Deterministic Finite Automaton (DFA) Solved Example

6. Design DFA for a L= {w | w has length <= 2} over Σ={0,1}

DFA M6 is = (Q, Σ, δ, q0, F)

Where

  1. Q : {q0, q1, q2,q3}
  2. Σ : {a, b}
  3. δ = Q × Σ -> Q =
    • δ(q0, a) = q1
    • δ(q0, b) = q1
    • δ(q1, a) = q2
    • δ(q1, b) = q2
    • δ(q2, a) = q3
    • δ(q2, b) = q3
    • δ(q3, a) = q3
    • δ(q3, b) = q3
    •  
  1. q0 : q0.
  2. F : {q0,q1,q2}

 

Note: The transition function can also be described with a transition table.

7. Design DFA that accepts all strings with odd number of a's, over Σ = {a, b}

DFA M7 is = (Q, Σ, δ, q0, F)

Where

  1. Q : {q0, q1}
  2. Σ : {a, b}
  3. δ = Q × Σ -> Q =
    • δ(q0, a) = q1
    • δ(q0, b) = q0
    • δ(q1, a) = q0
    • δ(q1, b) = q1
  1. q0 : q0.
  2. F : {q1}

 Note: The transition function can also be described with a transition table.

8. Design DFA for a L= {w | w starts with ab) over Σ={a,b}

DFA M8 is = (Q, Σ, δ, q0, F)

Where

  1. Q : {q0, q1, q2,q3}
  2. Σ : {a, b}
  3. δ = Q × Σ -> Q =
    • δ(q0, a) = q1
    • δ(q0, b) = q3
    • δ(q1, a) = q3
    • δ(q1, b) = q2
    • δ(q2, a) = q2
    • δ(q2, b) = q2
    • δ(q3, a) = q3
    • δ(q3, b) = q3
      •  
  1. q0 : q0.
  2. F : {q2}

 

Note: The transition function can also be described with a transition table.

9. Design DFA for a L= {w | number of a's in w is less than or equal to two.) over Σ={a,b}

DFA M9 is = (Q, Σ, δ, q0, F)

Where

  1. Q : {q0, q1, q2,q3}
  2. Σ : {a, b}
  3. δ = Q × Σ -> Q =
    • δ(q0, a) = q1
    • δ(q0, b) = q0
    • δ(q1, a) = q2
    • δ(q1, b) = q1
    • δ(q2, a) = q3
    • δ(q2, b) = q2
    • δ(q3, a) = q3
    • δ(q3, b) = q3
  1. q0 : q0.
  2. F : {q0,q1,q2}

 

Note: The transition function can also be described with a transition table.

10. Design DFA for a L= {w | number of a's in w is greater than or equal to two.}

DFA M10 is = (Q, Σ, δ, q0, F)

Where

  1. Q : {q0, q1, q2}
  2. Σ : {0, 1}
  3. δ = Q × Σ -> Q =
    • δ(q0, 0) = q1
    • δ(q0, 1) = q0
    • δ(q1, 0) = q0
    • δ(q1, 1) = q1
  1. q0 : q0.
  2. F : {q0}

 

Note: The transition function can also be described with a transition table.