Which one of the following is FALSE?

2017

Which one of the following is FALSE?

  1. A.

    There is a unique minimal DFA for every regular language

  2. B.

    Every NFA can be converted to an equivalent PDA

  3. C.

    Complement of every context-free language is recursive

  4. D.

    Every non-deterministic PDA can be converted to an equivalent deterministic PDA

Attempted by 66 students.

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Correct answer: D

Option A is true because minimal DFAs are unique up to isomorphism for regular languages. Option B holds since regular languages recognized by NFAs are a subset of context-free languages recognized by PDAs. Option C is true because recursive languages are closed under complementation and contain all CFLs. However, Option D is false; non-deterministic PDAs are strictly more powerful than deterministic ones, and no general conversion exists. Therefore, Option D is the correct answer.

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