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GATE 2017 · CS2 - Afternoon
Theory of ComputationTuring Machine: RE, REC and UndecidabilitymediumMCQ2 marks
Let L(R) be regular, L(G) be context-free, and L(M) be Turing acceptable. Which of the following decision problems are undecidable? I. Given a regular expression R and a string w, is w ∈ L(R)? II. Given a context-free grammar G, is L(G) = ∅? III. Given a context-free grammar G, is L(G) = Σ* for some alphabet Σ? IV. Given a Turing machine M and a string w, is w ∈ L(M)?
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