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Module 1: Introduction & Regular Languages

20242m

NFA has 'non-deterministic' in its name because:

(i) The result is undetermined
(ii) The choice of path is nondeterministic
(iii) The next state is nondeterministic
(iv) All of the mentioned

Worked SolutionAI Assisted

Answer

Correct Option: (ii) The choice of path is nondeterministic (and equivalently (iii); if “All of the mentioned” is offered, (iv) is also defensible)

Explanation

Deterministic FA: δ:Q×Σ→Q\delta: Q \times \Sigma \rightarrow Q — exactly one next state for each (q,a)(q,a).

Nondeterministic FA: δ:Q×Σ→2Q\delta: Q \times \Sigma \rightarrow 2^{Q} — a set of possible next states. The machine may:

  • be in several states simultaneously (subset view), or
  • guess a path.

So “non-deterministic” means:

  • Next state is not uniquely determined → (iii)
  • Choice of computation path is nondeterministic → (ii)

The “result” (accept/reject) is determined (exists some accepting path ⇔ accept), so (i) “result undetermined” is misleading.

In many textbooks the canonical answer is (ii) Choice of path is nondeterministic (or (iii)). If option (iv) “All of the mentioned” lumps (ii)+(iii), some keys mark (iv) as correct.

Formal

N=(Q,Σ,δ,q0,F)N = (Q,\Sigma,\delta,q_0,F), δ(q,a)={p1,p2,… }\delta(q,a) = \{p_1,p_2,\dots\}. On input ww, NN accepts iff there exists a path q0→wf∈Fq_0 \xrightarrow{w} f\in F.

Final Answer

NFA is nondeterministic because the next state / path is not uniquely determined → Option (ii) (and (iii)).

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