UGC NET COMPUTER SCIENCE SOLVED PAPERS 2017-19 - UGC NET Computer Science November 2017 Paper 3

62. Context free grammar is not closed under:

  • Option : B
  • Explanation :
    Context free grammar are not closed under Complementation. So, option (B) is correct.
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63. Consider the following languages: L1 = {am bn │ m ≠ n} L2 = {am bn │ m = 2n+1} L3 = {am bm │ m ≠ 2n} Which one of the following statement is correct ?

  • Option : D
  • Explanation :
    1. In L1 we have to check for m is not equal to n. there are infinite no which falls under this category but we have only one comparision with m and n. So it is context free language.
    2. In L2 one comparison with infinite possibilities of m and n, it is alos a CFL
    3. In L3 one comparison with infinite possibilities of m and n, it is alos a CFL
    So, option (D) is correct.
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