InterviewSolution
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Which of the following languages are undecidable? Note that ⟨M⟩ indicates encoding of the Turing machine M.L1 = { ⟨M⟩ ∣ L(M)=∅ }L2 = { ⟨M,w,q⟩ ∣ M on input w reaches state q in exactly 100 steps }L3 = { ⟨M⟩ ∣ L(M) is not recursive }L4 = { ⟨M⟩ ∣ L(M) contains at least 21 members }(A) L1, L3, and L4 only(B) L1 and L3 only(C) L2 and L3 only(D) L2, L3, and L4 only |
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