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## MCQs TOC|UGC-NET|GATE|Computer Science

 11. A Context free Grammar is ambiguous if A. The grammar contains useless non-terminals. B. It Produces more than one parse tree for some sentence. C. Some production has two non-terminals side by side on the right hand side. D. None of the Above. View/Hide Ans Explanation 12. CFLs and regular languages are both closed under the operations of A. Union B. Intersection C. Complementation D. Concatenation View/Hide Ans Explanation 13. Which of the Following problems are undecidable ? A. Membership problem in context free languages. B. Whether a given context - free language is regular. C. Whether a finite state automation halts on all inputs. D. Membership problem for Type 0 languages. View/Hide Ans Explanation 14. Recursive languages are : A. A proper superset of context free languages. B. Always recognizable by pushdown automata. C. Also called Type 0 languages. D. Recognizable by Turing Machines. View/Hide Ans Explanation 15. It is undecidable whether A. An arbitrary Turing machine halts after ten steps. B. A Turing machine prints a specific letter. C. A Turing machine computes the product of two numbers. D. None of the above. View/Hide Ans Explanation 107. Automaton accepting the regular expression of any number of a ' s is: A. a* B. ab* C. (a/b)* D. a*b*c View/Hide Ans Explanation 108. Grammars that can be translated to DFAs: A. Left linear grammar B. Right linear grammar C. Generic grammar D. All of these View/Hide Ans Explanation 109. The language accepted by a Push down Automata: A. Type0 B. Type1 C. Type2 D. Type3 View/Hide Ans Explanation 110. Given the following statements : (i) Recursive enumerable sets are closed under complementation. (ii) Recursive sets are closed under complementation. Which is/are the correct statements ? A. only (i) B. only (ii) C. both (i) and (ii) D. neither (i) nor (ii) View/Hide Ans Explanation 111. Q. Assume statements S1 and S2 defined as : S1 : L2-L1 is recursive enumerable where L1 and L2 are recursive and recursive enumerable respectively. S2 : The set of all Turing machines is countable. Which of the following is true ? A. S1 is correct and S2 is not correct. B. Both S1 and S2 are correct. C. Both S1 and S2 are not correct. D. S1 is not correct and S2 is correct. View/Hide Ans Explanation

Author Does Not claim of any answer these answers are as per expert opinion

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