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GATE 2020
Theory of ComputationTuring Machine: RE, REC and UndecidabilityhardMCQ2 marks
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 }
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