Gujarat Technological UniversitySummer 2026 Examination

GTU 3140708 Discrete Mathematics (DM) Summer 2026 Paper Solution & PDF

B.E. · Computer Engineering · Semester 4 · Subject Code: 3140708
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Total Marks70 MarksExternal theory exam
Passing Marks23 Marks33% minimum cutoff
Exam Duration2.5 Hours10:30 AM – 1:00 PM
Paper Structure5 QuestionsWith internal OR choices
Jump toQ1Q2Q3Q4Q5

Question 1

14 MarksMedium
(a)

Out of the integers 1 to 1000. How many of them are neither divisible by 3, nor by 5 nor by 7?

3 Marks
(b)
Define with an example
i)complete graph
ii)Tree
iii)Adjacency matrix
iv)strongly connected graph
4 Marks
(c)

Define partition of a set. Let a relation R is defined by xRy iff (x-y) is divisible by 5. Then show that R is an equivalence relation. Also, find the all distinct partition for R.

7 Marks

Question 2

14 MarksMedium
(a)
How many rectangles are there in 8×8 chessboard?
3 Marks
(b)
Define
i)partial ordered relation with an example.
ii)complemented lattice
iii)maximal element in POSET
4 Marks
(c)

Define the relation divisibility on the set D12. where D12 is the set of all positive divsors of 12.(i) show that it is an partial orderd relation

ii)Draw Hassse digram
iii)Is it a lattice? Justify
iv)find the least and greatest element.
v)give two chains from POSET.
7 Marks
OR OPTION
(c)
Solve the recurrence relation:
7 Marks

Question 3

14 MarksMedium
(a)

Show that the function from R to R defined by f(x)=4x+8 is one-one and onto. Also, find the inverse.

3 Marks
(b)
(
i)Define the semigroup and give an example of it.
ii)Give an example which is semigroup but not monoid with justification.
4 Marks
(c)

Define the isomorphic graphs. Show that following two graphs are isomorphic with defined one-one correspondence between vertices.

7 Marks
OR OPTION
(a)

Find the minimum number of students needed to guarantee that five of them belong to the same class.

3 Marks
(b)

Define integral domain. show that the set Z6={[0], [1], [2], [3], [4], [5]} is not an integral domain.

4 Marks
(c)

Use warshall's algorithm to find the path between each pair of vertices for given directed graph

7 Marks

Question 4

14 MarksMedium
(a)
Show that
3 Marks
(b)
Show that (Z,+) is an commutative group.
4 Marks
(c)

Show that the set Z5={[0],[1],[2],[3],[4]} is the field under the operation addition modulo 5 and multiplication modulo 5.

7 Marks
OR OPTION
(a)

Find the inverse, converse and contrapositive of the statement: ‘’If there is vacation then i will go to Goa'

3 Marks
(b)

Show that the set {-i,i,1,-1} is the abelian group with usual multiplication. Also, show that it is cyclic group.

4 Marks
(c)

Define a ring. Show that set of all 3×3 matrices with real entries forms a ring with usual matrix addition and matrix multiplication.

7 Marks

Question 5

14 MarksMedium
(a)
Obtain the pcnf of the expression
3 Marks
(b)

Let (Z,+) be a group. Consider the set H= {5n: n is an integer}. show that H is subgroup of Z. Find the all cosets of H in Z.

4 Marks
(c)
Define
i)Path
ii)strongly connected graph
iii)k-regular graph.
iv)Indegree
v)How many nodes are necessary to construct a graph with exactly eight edges in which each node is of degree 2.
7 Marks
OR OPTION
(a)

There are two shopping malls next to each other. A with the sign board as “Good items are not cheap' and B with sign board as “Cheap items are not good”. Covert this into symbolic proposition. Do they mean same?

3 Marks
(b)

Define the identity element of a group. For the set of integer a binary operation is defined by x*y=x+y-2 . Find the identity element and inverse of each integer.

4 Marks
(c)

Define cycle in a graph. For the given tree find the pre order post order and in order traversal.

7 Marks
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About this Examination Paper & Attribution

Official Gujarat Technological University (GTU) examination paper and step-by-step solutions for Discrete Mathematics (DM) (Summer 2026, B.E. · Computer Engineering, Sem 4). Features complete 70-mark regular & remedial examination pattern, official marking distribution across all 5 questions, and direct 1-click official PDF download.

Transcribed for student exam preparation from Gujarat Technological University official examination archives. Questions, syllabus guidelines, and curriculum marking schemes remain the intellectual property of Gujarat Technological University.

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