THEORY OF COMPUTER SCIENCE (TCS) MAY 2013 COMPUTER SCIENCE SEMESTER 5
Con. 6972-13. GS-9099
(3 Hours) [Total Marks : 100]
N.B. (1) Question No.
1 is
compulsory.
(2) Attempt any
four questions from remaining
six questions.
(3) Draw suitable
diagrams wherever
necessary.
(4) Assume
suitable data, if
necessary.
(5)
Maximum weightage is given to technical
notations.
1. (a) | Define the following terms :- | 5 |
| (i) Undecidability |
| (ii) Unrestricted grammar |
| (iii) Pumping lemma. |
(b) | Define TM and Give its variants. | 5 |
(c) | Explain Chomsky hierarchy for formal languages. | 5 |
(d) | Give the closure properties of regular languages. | 5 |
2. (a) |
(i) What is ambiguous CFG ? Give one example of ambiguous CFG. | 5 |
| (ii) What is Myhill-Nerode theorem ? Explain necessity of it. | 5 |
(b) | Let G be the grammar, find the leftmost derivation , right most derivation and parse | 10 |
| tree for the string 00110101 |
| S → OB / 1A |
| A → O/OS/1AA |
| B → 1/1S/OBB |
3. (a) |
Explain CNF and GNF with example. |
10 |
(b) | Give the formal definition of RE and design a DFA corresponding to the regular | 5 |
| expression |
| (a+b) * aba (a+b)* |
(c) | Using pumping lemma prove that the following language is regular or not | 5 |
|
|
4. (a) | Write NFA for accepting the following RE | 10 |
| (a+bb)* + ϵ) |
(b) | Explain DPDA and NPDA with languages of them. | 10 |
5. (a) |
Find the languages defined by the following grammar : |
10 |
| (i) S → OA/ IC |
| A → OS / IB / ϵ |
| B → 1A / OC |
| C → OB / 1S |
| (ii) S → OA / IC |
| A → OS / IB |
| B → OC / IA / ϵ |
| C → OB / IS |
(b) | Construct the PDA accepting following language | 10 |
| |
6. (a) |
Differentiate between Moore and Mealy machine with proper example and usage |
10 |
| Cary out conversion of Moore MIC to Mealy MIC. |
(b) | Design a Turing machine to accept the language | 10 |
|
|
7. Write short notes on any
four :-
20
(a) Recursive and recursively enumerable languages
(b) Intractable problems
(c) Simplification of CFGs
(d) Decision properties of regular languages
(e) Rice's theorem.
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