Discrete Structures & Theory of Logic Unit 3 – Theory of Logic: AKTU previous year questions

37 AKTU questions from Unit 3 (Theory of Logic) asked in 2020–2026, tagged by marks, year and topic. In short: about 38 marks of every paper come from this unit; the most asked topic is Propositional Logic (19 times); 12 questions came back in a later year. The latest ones are listed below; on the page you can filter them by 2-mark or long questions, topic and repeats.

Unit 3 previous year questions

Prove that the statement “if n is an integer, then n2-n+4! Is a prime number” is false. (7 marks, 2026, Theory of Inference)
Explain the following terms with suitable example: (i) Converse (ii) Disjunction (iii) Conjunction (7 marks, 2026, Propositional Logic)
Translate the following statements in symbolic form: (i) The sum of two positive integer is always positive. (ii) Everyone is loved by someone. (iii) Some people are not admired by everyone. (iv) If a person is female and is a parent, then this person is someone’s mother. (7 marks, 2026, Predicate Logic)
What is meant by an existential quantifier? Explain it with a simple statement. (2 marks, 2026, Predicate Logic)
Analyse the argument's validity: Premises: If a person is happy, they smile. John is smiling. Conclusion: John is happy. (7 marks, 2025, Theory of Inference)
Justify that the following premises are inconsistent. (i) If Alex misses many classes through illness then he fails high school. (ii) If Alex fails high school, then he is uneducated. (iii) If Alex reads a lot of books then he is not uneducated. (iv) Alex misses many classes through illness and reads a lot of books. (7 marks, 2025, Theory of Inference)
Show the validity of the following argument: Hypotheses: “It is not sunny this afternoon and it is colder than yesterday. We will go swimming only if it is sunny. If we do not go swimming, then we will take a canoe trip. If we take a canoe trip, then we will be home by sunset. Conclusion: “We will be home by sunset.” (7 marks, 2025, Theory of Inference)
Construct inverse of the following statement “If I wake up early in the morning, then I will be healthy.” (2 marks, 2024, Theory of Inference)
Show the validity of the following argument: hypotheses: “It is not sunny this afternoon and it is colder than yesterday. We will go swimming only if it is sunny. If we do not go swimming, then we will take a canoe trip. If we take a canoe trip, then we will be home by sunset. conclusion: “We will be home by sunset.” (7 marks, 2024, Theory of Inference)
Test the validity of the following argument. “If there was a ball game, then traveling was difficult. If they arrived on time, then traveling was not difficult. They arrived on time. Therefore, There was no ball game.” (7 marks, 2024, Theory of Inference)
Describe ∃ and ∀ Quantifiers with example. “There is someone who got an A in the course” convert this sentence into predicate logic using quantifiers. Prove the following argument. All man are mortal. Socrates is a man. Therefore, Socrates is mortal. (7 marks, 2024, Predicate Logic)
Identify whether (p Λ q) → (p V q) is tautology or contradiction with using Truth table. (2 marks, 2023, Propositional Logic)

Most asked Unit 3 topics

Propositional Logic – asked 19 times
Theory of Inference – asked 13 times
Predicate Logic – asked 5 times

Unit 3 question pattern

2-mark questions: 10 asked in 2020–2026
7-mark questions: 9 asked in 2020–2026
10-mark questions: 18 asked in 2020–2026
About 38 marks from Unit 3 in every paper
12 questions were asked again in a later year

Unit 3 questions year by year

2026: 4 Unit 3 questions asked (23 marks across that year's papers)
2025: 3 Unit 3 questions asked (21 marks across that year's papers)
2024: 4 Unit 3 questions asked (23 marks across that year's papers)
2023: 4 Unit 3 questions asked (32 marks across that year's papers)
2022: 6 Unit 3 questions asked (36 marks across that year's papers)
2021: 11 Unit 3 questions asked (86 marks across that year's papers)
2020: 5 Unit 3 questions asked (42 marks across that year's papers)