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Previous Year Question Paper

(CSE)-302 – Discrete Structure

June 2025CSESEMESTER-3
June 2025
Max Marks: 70
Duration: 3 Hours
Instructions:

Attempt any five questions.

All questions carry equal marks.

Q.1
a)Unit 1

Consider three sets A = {1, 2, 3, 4, 5}, B = {3, 4, 5, 6} and C = {1, 5, 7}. Using Venn diagrams, determine and shade the regions corresponding to (A ∪ B) ∩ (B ∩ C) and A ∩ (B ∪ C). Verify if these expressions are equivalent by listing the elements.

b)Unit 1

Define and illustrate an equivalence relation by constructing an equivalence relation on the set S = {1, 2, 3, 4, 5, 6} where two elements are related if they have the same remainder when divided by 3.

Q.2
a)Unit 1

What is pigeonhole principle? Prove it by using mathematical induction and use it to show that in a group of 15 people, at least two share the same birth month.

b)Unit 5

Explain a recursively defined function. Solve the recurrence relation f(n) = f(n-1) + 3 with initial condition f(0) = 2.

Q.3
a)Unit 2

Prove that the set G = {0, 1, 2, 3} under addition modulo 4 is an abelian group. Identify the identity and inverse elements.

b)Unit 2

Define a homomorphism between two groups. Verify whether the mapping f: R → R defined by f(x) = 2x is a homomorphism under addition.

Q.4
a)Unit 3

Consider the propositions p, q and r, where: p: "It is raining." q: "I am carrying an umbrella." r: "I stay dry." Assume the implication (p → q) → r. Construct a truth table for the expression (p → q) → r and determine if it is a tautology or contradiction.

b)Unit 3

What are predicates in propositional logic? Define universal and existential quantifiers with examples.

Q.5
a)Unit 4

Define graph theory and explain the basic terminology of graphs such as vertices, edges, degree and adjacency.

b)Unit 4

Define and give an example of an isomorphic graph pair. Verify isomorphism between two adjacency matrices.

Q.6
a)Unit 4

For the graph G with vertices V = {A, B, C, D} and edges E = {(A, B), (B, C), (C, D), (D, A), (A, C)}, determine:

i) Whether the graph contains a Eulerian path or circuit or not.

ii) All Hamiltonian circuits in the graph G.

b)Unit 5

How many permutations can be formed from the letters of the word “MATHEMATICS” such that all vowels are together?

Q.7
a)Unit 5

What is a Hasse diagram? Draw the Hasse diagram for the set {1, 2, 3, 6, 9, 18} with the divisibility relation.

b)Unit 5

Define a lattice and prove that every finite lattice has a unique least upper bound and greatest lower bound.

Q.8
Unit 3, Unit 5, Unit 2, Unit 1, Unit 1

Write short notes on (any four):

i) Finite state machines as language recognizers

ii) Binomial theorem

iii) Permutation group

iv) Partial Ordering Relation

v) Countable and uncountable sets