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

122. | The following CFG S -> aB | bA, A -> a | as | bAA B -> b | bs | aBB generates strings of terminals that have |

A. | odd number of a’s and odd number of b’s |

B. | even number of a’s and even number of b’s |

C. | equal number of a’s and b’s |

D. | not equal number of a’s and b’s |

View/Hide Ans | |

Explanation | |

123. | Consider the following statements : I. Recursive languages are closed under complementation. II. Recursively enumerable languages are closed under union. III. Recursively enumerable languages are closed under complementation. Which of the above statements are true ? |

A. | I only |

B. | I and II |

C. | I and III |

D. | II and III |

View/Hide Ans | |

Explanation | |

124. | Given the following statements : (i) The power of deterministic finite state machine and nondeterministic finite state machine are same. (ii) The power of deterministic pushdown automaton and nondeterministic pushdown automaton are same. Which of the above is the correct statement(s) ? |

A. | Both (i) and (ii) |

B. | Only (i) |

C. | Only (ii) |

D. | Neither (i) nor (ii) |

View/Hide Ans | |

Explanation | |

125. | Given the following productions of a grammar : S? aA| aBB; A?aaA |? ; B? bB| bbC; C? B Which of the following is true ? |

A. | The language corresponding to the given grammar is a set of even number of a’s. |

B. | The language corresponding to the given grammar is a set of odd number of a’s. |

C. | The language corresponding to the given grammar is a set of even number of a’s followed by odd number of b’s. |

D. | The language corresponding to the given grammar is a set of odd number of a’s followed by even number of b’s. |

View/Hide Ans | |

Explanation | |

202. | P, Q, R are three languages. If P & R are regular and if PQ=R, then |

A. | Q has to be regular |

B. | Q cannot be regular |

C. | Q need not be regular |

D. | Q has to be a CFL |

View/Hide Ans | |

Explanation | |

204. | Consider the grammar given below E? E+E | E*E | E-E | E/E | E^E | (E) | id Assume that + and – have the same but least precedence, * and / have the next higher precedence but the same precedence and finally ^ has the highest precedence. Assume + and – associate to the left like * and / and that ^ associates to the right. Choose the correct statement with respect to relations for the ordered pairs (^,^) , (-,-) , (+,+) , (*,*) in the operator precedence table constructed for the grammar |

A. | all < |

B. | all > |

C. | <,>,=,< |

D. | <,>,>,> |

View/Hide Ans | |

Explanation |

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