Set Theory & Algebra

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Question 1

The time complexity of computing the transitive closure of a binary relation on a set of n elements is known to be

  • O(n*log(n))

  • O(n3/2)

  • O(n3)

  • O(n)

Question 2

Given a boolean function f (x1, x2, ..., xn), which of the following equations is NOT true

 

  • f(x1​, x2​, …, xn​) = x1'f(x1​, x2​, …, xn​) + x1​f(x1​, x2​, …, xn​)

  • f(x1, x2, ..., xn) = x2f(x1, x2, …, xn) + x2'f(x1, x2, …, xn)

  • f(x1, x2, ..., xn) = xn'f(x1, x2, …, 0) + xnf(x1, x2, …,1)

  • f(x1, x2, ..., xn) = f(0, x2, …, xn) + f(1, x2, ..., xn)

Question 3

A binary operation ⊕ on a set of integers is defined as x ⊕ y = x2 + y2. Which one of the following statements is TRUE about ⊕?

  • Commutative but not associative

  • Both commutative and associative

  • Associative but not commutative

  • Neither commutative nor associative

Question 4

Consider the set S = {1, ω, ω2}, where ω and w2 are cube roots of unity. If * denotes the multiplication operation, the structure (S, *) forms

  • A group

  • A ring

  • An integral domain

  • A field

Question 5

Which one of the following in NOT necessarily a property of a Group?

  • Commutativity

  • Associativity

  • Existence of inverse for every element

  • Existence of identity

Question 6

Consider the binary relation R = {(x, y), (x, z), (z, x), (z, y)} on the set {x, y, z}. Which one of the following is TRUE?

  • R is symmetric but NOT antisymmetric

  • R is NOT symmetric but antisymmetric

  • R is both symmetric and antisymmetric

  • R is neither symmetric nor antisymmetric

Question 7

For the composition table of a cyclic group shown below

 

Which one of the following choices is correct?

  • a, b are generators

  • b, c are generators

  • c, d are generators

  • d, a are generators

Question 8

The number of students in three classes is in the ratio 3:13:6. If 18 students are added to each class, the ratio changes to 15:35:21. The total number of students in all the three classes in the beginning was:

  • 22

  • 66

  • 88

  • 110

Question 9

If P, Q, R are subsets of the universal set U, then the value of following expression is

(PQ  R) ∪ (Pc  Q  R) ∪ Qc ∪ Rc


  • Qc U Rc
     

  • P U Qc U Rc
     

  • Pc U Qc U Rc
     

  • U
     

Question 10

Let S be a set of n elements. The number of ordered pairs in the largest and the smallest equivalence relations on S are:

  • n and n

  • n2 and n

  • n2 and 0

  • n and 1

There are 121 questions to complete.

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