Compilers

Context Free Grammar

Question 1
Marks : +2 | -2
Pass Ratio : 100%
The context free grammar S → A111|S1, A → A0 | 00 is equivalent to _________
{0n1m | n=2, m=3}
{0n1m | n=1, m=5}
{0n1m | n should be greater than two and m should be greater than four}
None of the mentioned
Explanation:
S-> A111
Question 2
Marks : +2 | -2
Pass Ratio : 100%
A regular Grammar is a _________
CFG
Non CFG
English Grammar
None of the mentioned
Explanation:
Regular grammar is CFG. It restricts its rules to a single non terminal on left hand side.
Question 3
Marks : +2 | -2
Pass Ratio : 100%
Which of the following statement is false?
In derivation tree, the label of each leaf node is terminal
In derivation tree, the label of all nodes except leaf nodes is a variable
In derivation tree, if the root of a sub tree is X then it is called –tree
None of the mentioned
Explanation:
All of them are true regarding a derivation tree.
Question 4
Marks : +2 | -2
Pass Ratio : 100%
Recursively enumerable languages are not closed under ______________
Union
Intersection
Complementation
Concatenation
Explanation:
Recursive languages are closed under the following operations.
Question 5
Marks : +2 | -2
Pass Ratio : 100%
Which of the following conversion is not possible (algorithmically)?
Regular grammar to CFG
NDFA to DFA
NDPDA to DPDA
NDTM to DTM
Explanation:
Not every NDPDA has an equivalent deterministic PDA.
Question 6
Marks : +2 | -2
Pass Ratio : 100%
Which of the following statement is false?
The CFG can be converted to Chomsky normal form
The CFG can be converted to Greibach normal form
CFG is accepted by pushdown automata
None of the mentioned
Explanation:
All the statements follow the rules.
Question 7
Marks : +2 | -2
Pass Ratio : 100%
If P & R are regular and also given that if PQ=R, then?
Q has to be regular
Q cannot be regular
Q need not be regular
Q has to be a CFL
Explanation:
If two regular languages when combined do not always produce a regular language.
Question 8
Marks : +2 | -2
Pass Ratio : 100%
Consider the grammar given below E? E+E | E*E | E-E | E/E | E^E | (E) | id Assume that + and ^ have the same but least precedence, * and / have the next higher precedence but the same precedence and finally ^ has the highest precedence. Assume + and ^ associate to the left like * and / and that ^ associates to the right. Choose the correct for the ordered pairs (^,^), (-,-), (+,+), (*,*) in the operator precedence table constructed for the grammar.
All <
All >
< >, =
< > > >
Explanation:
This relation is established of basis of the precedence of operators.
Question 9
Marks : +2 | -2
Pass Ratio : 100%
Given the following statements: (i) Recursive enumerable sets are closed under complementation. (ii) Recursive sets are closed under complements. Which is/are the correct statements?
I only
II only
Both I and II
Neither I nor II
Explanation:
Recursive languages are closed under the following operations.
Question 10
Marks : +2 | -2
Pass Ratio : 100%
Assume the statements S1 and S2 given as:
S1 is correct and S2 is not correct
Both S1 and S2 are correct
Both S1 and S2 are not correct
S1 is not correct and S2 is correct
Explanation:
The proof of S1 can be seen in various book of theory of computation but s2 is a problem of category undecidable so a contradiction to this assumption can be easily obtained.