CSC262 Theory of Computation

Theory of Computation TU Board 2076 question paper

12 questionsSit this paper (timed)

Tribhuvan University

Bachelor of Science in Computer Science and Information Technology

Semester 4 · TU Board 2076

Course Title: Theory of Computation (CSC262)

Full Marks: 60Pass Marks: 24Time: 3 hours

Candidates are required to give their answers in their own words as far as practicable. The figures in the margin indicate full marks.

Group A

Attempt any Two questions. (2x10=20)(2 × 10 = 20)

  1. 1.

    Define the NFA with ε-transition and ε-closure of a state. Show that for every regular expression r, representing a language L, there is ε-NFA accepting the same language. Also convert regular expression (a+b)ab into equivalent Finite Automata.

    10
  2. 2.

    How can you define the language accepted by a PDA? Explain how a PDA accepting language by empty stack is converted into an equivalent PDA accepting by final state and vice-versa.

    10
  3. 3.

    Define a Turing machine. Construct a TM that accept L = {wcw^R | w∈(0, 1) and c is ε or 0 or 1. Show that string 0110 is accepted by this TM with sequence of Instantaneous Description (ID).

    10

Group B

Attempt any Eight questions. (8x5=40)(8 × 5 = 40)

  1. 4.

    Give the formal definition of DFA. Construct a DFA accepting all strings of {0, 1} with even number of 0's and even number of 1's.

    5
  2. 5.

    Define Chomsky Normal Form and Greibach Normal Form in reference to CFG. Give a suitable example of each.

    5
  3. 6.

    Give the regular expressions for following language over alphabet {0, 1}.

    1. Set of all strings with 2^nd symbol from right is 1.
    2. Set of all strings starting with 00 or 11 and ending with 10 or 01.
    5
  4. 7.

    Show that language L={0^m1^m | m>=1} is not a regular language.

    5
  5. 8.

    Describe the Turing machines with multiple tape, multiple track and storage in state.

    5
  6. 9.

    Construct a NFA accepting language of {0, 1} with each string ending with 01 and convert it into equivalent DFA.

    5
  7. 10.

    Construct a PDA accepting language over {0, 1} representing strings with equal no of 0s and1s. Show by sequence of IDs that 0101 is accepted by this PDA.

    5
  8. 11.

    Define complexity of a Turing machine. Explain about big Oh, big Omega and big Theta notation used for complexity measurement.

    5
  9. 12.

    What do you mean by tractable and Intractable problems? Explain with reference to TM.

    5

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