Theory of Automata and Formal Languages Unit 2 – Regular Expressions and Languages: important questions for AKTU
Unit 2 (Regular Expressions and Languages) questions that AKTU repeats most often. This unit carries about 31 marks per paper. Start with the repeated questions, then the most asked topics.
Most repeated Unit 2 questions
- Using Pumping Lemma, show that the language L = {aⁿbⁿcⁿ | n ≥ 0} is not regular. (7 marks, 2025, Pumping Lemma for Regular Languages) – also asked in 2018, 2019, 2022, 2023, 2024
- Prove using Arden's Theorem the regular expression for the following transition diagram: States: A (start), B (final). Transitions: A --a--> A, A --b--> B, B --a--> B (7 marks, 2025, Arden's Theorem) – also asked in 2018, 2019, 2023, 2024
- Discuss closure properties (i.e. union, concatenation, complement, intersection and difference) of regular language. (7 marks, 2024, Closure Properties of Regular Languages) – also asked in 2018, 2019, 2022, 2023
Most important Unit 2 topic
- Regular Expressions (Unit 2: Regular Expressions and Languages) – asked 7 times in 2018, 2019, 2022, 2023, 2024, 2025
Most asked Unit 2 topics
- Regular Expressions – asked 7 times
- Arden's Theorem – asked 7 times
- Pumping Lemma for Regular Languages – asked 7 times
More Unit 2 previous year questions
- Write the regular expression for the language containing strings over {0,1} ending with 01. (2 marks, 2025, Regular Expressions)
- Prove that (a+b)*a(a+b)* is a regular language using Arden's Theorem. (7 marks, 2025, Arden's Theorem)
- Give regular expressions that represent the language (L), which has all binary strings having two consecutive 0s and two consecutive 1s over the alphabet Σ = {0, 1}. (2 marks, 2024, Regular Expressions)
- Compute the regular expression using Arden's Theorem for the following DFA. (7 marks, 2024, Arden's Theorem)
- State Pumping Lemma for Regular Language. Show that the given language L={ap | Where p is a prime} is not regular. (7 marks, 2024, Pumping Lemma for Regular Languages)
Unit 2 syllabus topics
- Regular Expressions
- Arden's Theorem
- Closure Properties of Regular Languages
- Pumping Lemma for Regular Languages
- Decidability of Regular Languages