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# How to convert NFA with epsilon to without epsilon?

In this method, we try to remove all the ε-transitions from the given Non-deterministic finite automata (NFA) −

The method is mentioned below stepwise −

**Step 1**− Find out all the ε-transitions from each state from Q. That will be called as ε-closure(qi) where, qi ∈Q.**Step 2**− Then, 𝛿1 transitions can be obtained. The 𝛿1 transitions means an ε-closure on 𝛿 moves.**Step 3**− Step 2 is repeated for each input symbol and for each state of given NFA.**Step 4**− By using the resultant status, the transition table for equivalent NFA without ε can be built.

NFA with ε to without ε is as follows −

δ1(q,a) = ∈ - closure (δ (δ∈^(q,∈𝛜),a)) where, δ^(q,∈𝛜) = ∈ - closure(q)

## Example

Convert the given NFA with epsilon to NFA without epsilon.

## Solution

We will first obtain ε-closure of each state i.e., we will find ε-reachable states from the current state.

Hence,

- ε-closure(q0) = {q0,q1,q2}
- ε-closure(q1) = {q1,q2}
- ε-closure(q2) = {q2}

ε-closure(q0) means with null input (no input symbol) we can reach q0, q1, q2.

In a similar manner for q1 and q2 ε-closure are obtained.

Now we will obtain 𝛿1 transitions for each state on each input symbol as shown below −

δ'(q0, 0) = ε-closure(δ(δ^(q0, ε),0)) = ε-closure(δ(ε-closure(q0),0)) = ε-closure(δ(q0,q1,q2), 0)) = ε-closure(δ(q0, 0) ∪ δ(q1, 0) U δ(q2, 0) ) = ε-closure(q0 U Φ ∪ Φ) = ε-closure(q0) = {q0,q1, q2} δ'(q0, 1) = ε-closure(δ(δ^(q0, ε),1)) = ε-closure(δ(q0,q1,q2), 1)) = ε-closure(δ(q0, 1) ∪ δ(q1, 1) U δ(q2, 1) ) = ε-closure(Φ ∪q1 U Φ) = ε-closure(q1) = {q1, q2} δ'(q0, 2) = ε-closure(δ(δ^(q0, ε),2)) = ε-closure(δ(q0,q1,q2), 2)) = ε-closure(δ(q0, 2) ∪ δ(q1, 2) U δ(q2, 2) ) = ε-closure(Φ U ΦU q2) = ε-closure(q2) = {q2} δ'(q1, 0) = ε-closure(δ(δ^(q1, ε),0)) = ε-closure(δ(q1,q2), 0)) = ε-closure(δ(q1, 0) U δ(q2, 0) ) = ε-closure(Φ ∪ Φ) = ε-closure(Φ) = Φ δ'(q1,1) = ε-closure(δ(δ^(q1, ε),1)) = ε-closure(δ(q1,q2), 1)) = ε-closure(δ(q1, 1) U δ(q2, 1) ) = ε-closure(q1 ∪ Φ) = ε-closure(q1) = {q1,q2} δ'(q1, 2) = ε-closure(δ(δ^(q1, ε),2)) = ε-closure(δ(q1,q2), 2)) = ε-closure(δ(q1, 2) U δ(q2, 2) ) = ε-closure(Φ ∪ q2) = ε-closure(q2) = {q2} δ'(q2, 0) = ε-closure(δ(δ^(q2, ε),0)) = ε-closure(δ(q2), 0)) = ε-closure(δ(q2, 0)) = ε-closure(Φ) = Φ δ'(q2, 1) = ε-closure(δ(δ^(q2, ε),1)) = ε-closure(δ(q2), 1) = ε-closure(δ(q2, 1)) = ε-closure(Φ) = Φ δ'(q2, 2) = ε-closure(δ(δ^(q2, ε),)) = ε-closure(δ(q2), 2)) = ε-closure(δ(q2, 2)) = ε-closure(q2) = {q2}

Now, we will summarize all the computed δ' transitions as given below −

δ'(q0,0)={q0,q1,q2} δ'(q0,1)={q1,q2} δ'(q0,2)={q2} δ'(q1,0)= { Φ } δ'(q1,1)={q1,q2} δ'(q1,2)={q2} δ'(q2,0)={ Φ } δ'(q2,1)={ Φ } δ'(q2,2)={q2}

The **transition table** is given below −

States\inputs | 0 | 1 | 2 |
---|---|---|---|

q0 | {q0,q1,q2} | {q1,q2} | {q2} |

q1 | Φ | {q1,q2} | {q2} |

q2 | Φ | Φ | {q2} |

## NFA without epsilon

The NFA without epsilon is given below −

Here, q0, q1, q2 are final states because ε-closure(q0), ε-closure(q1) and ε-closure(q2) contain a final state q2.

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