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Module 1: Introduction & Regular Languages

20212m

The maximum number of states of a DFA converted from an NFA with nn states is:

(i) nn
(ii) n2n^2
(iii) 2n2^n
(iv) None of the above

Worked SolutionAI Assisted

Answer

Correct Option: (iii) 2n2^{n}

Explanation

NFA with nn states → DFA via subset construction:

Each DFA state is a subset of NFA states. NFA states set QNQ_N, ∣QN∣=n|Q_N|=n.

Number of distinct subsets = ∣P(QN)∣=2n|\mathcal{P}(Q_N)| = 2^{n}.

This includes ∅\emptyset (dead state).

Hence DFA has at most 2n2^{n} states. Upper bound is tight: there exist NFA families (e.g., language “nnth symbol from end is 1”) that require exactly 2n2^{n} DFA states.

Final Answer

Maximum 2n2^{n} states → Option (iii). (Minimal DFA may be smaller, but maximum is 2n2^{n}.)

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