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+18 votes

We require a four state automaton to recognize the regular expression $(a\mid b)^*abb$

  1. Give an NFA for this purpose
  2. Give a DFA for this purpose
asked in Theory of Computation by Veteran (52k points)
edited by | 737 views

1 Answer

+24 votes
Best answer

NFA for regular expression $(a+b)^*abb$ and its equivalent DFA will be as follows:

answered by Veteran (55.8k points)
edited by

@Praveen Saini Sir What is the meaning of (a/b)* the question,is it (a+b)* what they have meant?

yes, afai think
praveen sir u r the best toc expert ever i seen


state   a          b

qo     q0q1    q0

q1        ^         q2

q2       ^           q3

q3       ^           ^

q0q1     q0q1     q0q2

q0q2      q0q1     q0q3

q0q3       q0q1     q0


q3 is final state so q0q3 also final state. Total 6 states.

Where am I going wrong? Pls help @Praveen Saini


@ , there is no need of q1, q2 and q3 check once.


@Praveen Saini sir construct an NFA for regular expression (a+b)* abb  and then convert it into DFA, will that be okk sir ??

Yes, this is good, but it is a time-consuming process, we can make DFA from the regular expression.

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