Tribhuvan University
Institute of Science and Technology
2080-new
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 question.
Describe the extended transition function of NFA. Construct a NFA, using transition table and transition diagram , over {0, 1} that accept the string having substring 01 and ends with 1. Show the acceptance of 0111.
Define CFG. Construct a CFG that generates the language of all palindromes over {a,b} that do not contain the substring aa. Show the leftmost derevation and construct the equivalent parse tree for string babbbab.
How Turing Machine is used as a computing function? Construct a TM for simulating a function f(x) = 2x for x = {1}. Itetrate the TM for input 11 and generate the output 1111.
SECTION B
Attempt any EIGHT question.
Differentiate Kleen closure from positive closure. Compute positive and Kleen closure of {ab}.
Design a Melay machine over {a, b} that generates output ‘A’ if the input string ends with aa else output ‘B’ if the string ends with bb.
Construct regular expression over {1,2,….9} that represents
Prove that th language L ={an bn cn | n≥0} is not a context free grammar.
Construct a PDA that accepts string over Σ ={a,b} that contains equal number of a’s followed by equal number of b’s. Show acceptance of aabb and aab.
Describe how multi-stack TM is different from the semi-infinite tape TM?
What is intractability? Define time and space complexity of turing machine.
How conversion of PDA to CFG done ? Illustrate with example.
State Arden’s theorem. Convert following DFA into its regular expression using Arden theorem.
