Tribhuvan University
Institute of Science and Technology
Toc Model Qn
Bachelor Level / fourth-semester / Science
Computer Science and Information Technology( CSC262 )
Theory of Computation
Full Marks: 60 + 20 + 20
Pass Marks: 24 + 8 + 8
Time: 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.
Section A
Attempt any two questions.
Define the extended transition function of DFA. Draw a DFA accepting language L = {1n | n = 2, 3, 4…. }. Show acceptance of strings 1110011 and 1110 using extended transition function.
What is deterministic pushdown automaton? Configure a pushdown automaton accepting the language, L={w C wR | w ∈ (0,1)*}. Show instantaneous description of strings 011C110 and 10C10.
How a Turing Machine works? Construct a Turing machine accepting the language L = {(n)n}. Also show the transition diagram of the machine. Illustrate whether a string (()) is accepted by the Turing machine or not.
Section B
Attempt any eight questions.
When a grammar is said to be in CNF? Convert the following grammar to CNF:
S → 1A | 0B | ε
A → 1AA | 0S | 0
B → 0BB | 1 | A
C → CA | CS
Define epsilon NFA. Configure equivalent epsilon NFA for the regular expression (ab U a)*.
Differentiate Kleene closure from positive closure. For ∑ = {0,1}, compute ∑* and ∑2.
Write the regular expression over {0,1} for strings
What is undecidable problem? Define post’s correspondence problem with an example.
How pumping lemma can be used to prove that any language is not a regular language? Show that language, L = {0n1n | n>0} is not a regular language.
Discuss how Turing Machine with multiple tracks differs from a Turing Machine with multiple tapes.
How context free grammars are defined? Write a context free grammar over {0,1}, where the strings start and end with the same symbol.
What is halting problem? How can you argue that halting problem is undecidable?