U.G.C. NET Exam. Dec. 2020-June 2021 Paper II (COMPUTER SCIENCE & APPLICATIONS)

Total Questions: 100

31. Which of the following languages are not regular?

Correct Answer: (d) A, B and C
Solution:A, B and C , no one are regular

32. Any string of terminals that can be generated by the following context free grammar (where S is start non terminal symbol)

Correct Answer: (d) has at least two 0's
Solution:A language, which has at least two 0's

33. Answer the following question

Correct Answer: (a) A and B only
Solution:A and B are correct option.

34. Given below are two statements

Statement I: The family of context free languages is closed under homomorphism
Statement II: The family of context free languages is closed under reversal
In light of the above statements, choose the correct answer from the options given below :

Correct Answer: (a) Both Statement I and Statement II are true
Solution:Both Statement I and Statement II are true

35. What is the minimum number of states required to the finite automaton equivalent to the transition diagram given below?

Correct Answer: (c) 5
Solution:5

36. Find the regular expression for the language accepted by the automata given below.

Correct Answer: (e) *

37. What language is accepted by the pushdown automaton

Correct Answer: (d)
Solution:

38. Match List - I with List - II


Choose the correct answer from the options given below:

Correct Answer: (e)*

39. Which of the following concepts can be used to identify loops?

A. Depth first ordering
B. Dominators
C. Reducible graphs
Choose the correct answer from the options given below: 

Correct Answer: (d) A, B and C
Solution:

A Depth first ordering :- Depth - first search (DFS) is an algorithm for traversing or searching tree or graph data structures. The algorithm starts at the root node (selecting some orbitrary node as the root node in the case of a graph) and explores as for as possible along each branch before back tracking.
Vertex Orderings :-
i) pre ordering
ii) post ordering
iii) reverse preordering
iv) reverse postordering for binary trees there is additionally
e) in ordering
f) reverse in - ordering.
Dominators :- Dominators are defined in a directed graph with respect to a source, vertex S. formally, a node a is said to dominate a node w art source vertex S if all the paths from S to w in the graph must pass through node u. Note that only the vertices that are reachable from source vertex in the directed graph are considered here.
Reducible Graph :- A control how graph G is said to be reducible if the removal of its back edges leads to an acyclic graph where each node can be reached from the initial node of G.
So All above concepts can be used to identify loops

40. Given below are two statements

Statement I: LL(1) and LR are examples of Bottom‐up parsers.
Statement II: Recursive descent parser and SLR are examples of Top‐down parsers
In light of the above statements, choose the correct answer from the options given below:

Correct Answer: (b) Both Statement I and Statement II are false
Solution:Both Statement I and Statement II are false.