Computer Science and Information Technology
GATE CSE Discrete Mathematics PYQs
Build your understanding with focused practice from past exam papers.
How to practice Discrete Mathematics
Attempt a question, record the concept and assumptions, then check the available answer. Rework mistakes after revising the relevant concepts. Topic tags can overlap; review the question context.
Questions 1–10 of 35. Imported answers require independent review unless marked reviewed.
Question 10
Open questionGAMCQ2 marksNeeds review
The diagram below shows a river system consisting of 7 segments, marked P, Q, R, S, T, U, and V. It splits the land into 5 zones, marked Z1, Z2, Z3, Z4, and Z5. We need to connect these zones using the least number of bridges. Out of the following options, which one is correct?
Note: The figure shown is representative.

Your answerChoose one option.
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Open questionCSMCQ1 markNeeds review
Let
be an arbitrary predicate over the domain of natural numbers. Which ONE of the following statements is TRUE?Your answerChoose one option.
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Open questionCSMCQ1 markNeeds review
is a function from
to
,
is a function from
to
, and their composition defined as
is a mapping from
to
.If
and
are onto (surjective) functions, which ONE of the following is TRUE about the function
?Your answerChoose one option.
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 30
Open questionCSNAT1 markNeeds review
Let
be the set of all ternary strings defined over the alphabet
. Consider all strings in
that contain at least one occurrence of two consecutive symbols, that is, “aa”, “bb” or “cc”. The number of such strings of length 5 that are possible is ______. (Answer in integer)Log in to check the answer
You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 42
Open questionCSMSQ2 marksNeeds review
Let
be the set of all functions from
to
. Define the binary relation
on
as follows:
if and only if
, where
.Which of the following statement(s) is/are TRUE?
Your answerSelect all correct options. You can choose more than one.
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 48
Open questionCSMSQ2 marksNeeds review
Which of the following predicate logic formula/formula is/are CORRECT representation(s) of the statement: “Everyone has exactly one mother”? The means of the predicates used are:
:
is the mother of
:
and
are not equalYour answerSelect all correct options. You can choose more than one.
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 49
Open questionCSMSQ2 marksNeeds review
is the set of non-negative integers. Let F be the set of functions from A to itself. For any two functions,
, we define
for every number
in A. Which of the following is/are CORRECT about the mathematical structure
?Your answerSelect all correct options. You can choose more than one.
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Open questionCSNAT2 marksNeeds review
A quadratic polynomial
over complex numbers is said to be square invariant if
. Suppose from the set of all square invariant quadratic polynomials we choose one at random.The probability that the roots of the chosen polynomial are equal is __________. (rounded off to one decimal place)
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 12
Open questionCSMCQ1 markNeeds review
Let
and
be the following propositions:
: Fail grade can be given.
: Student scores more than 50% marks.Consider the statement: “Fail grade cannot be given when student scores more than 50% marks.”
Which one of the following is the CORRECT representation of the above statement in propositional logic?
Your answerChoose one option.
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 14
Open questionCS1MCQ1 markNeeds review
Consider a permutation sampled uniformly at random from the set of all permutations of
for some
. Let
be the event that 1 occurs before 2 in the permutation, and
the event that 3 occurs before 4. Which one of the following statements is TRUE?Your answerChoose one option.
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