1
GATE CSE 2003
MCQ (Single Correct Answer)
+2
-0.6
Define Languages $${L_0}$$ and $${L_1}$$ as follows
$${L_0} = \left\{ { < M,\,w,\,0 > \left| {M\,\,} \right.} \right.$$ halts on $$\left. w \right\}$$
$${L_1} = \left\{ { < M,w,1 > \left| M \right.} \right.$$ does not halts on $$\left. w \right\}$$

Here $$ < M,\,w,\,i > $$ is a triplet, whose first component, $$M$$ is an encoding of a Turing Machine, second component, $$w$$, is a string, and third component, $$t,$$ is a bit.
Let $$L = {L_0} \cup {L_1}.$$ Which of the following is true?

A
$$L$$ is recursively enumerable, but $$\overline L $$ is not
B
$$\overline L $$ is recursively enumerable, but $$L$$ is not
C
Both $$L$$ and $$\overline L $$ are recursive
D
Neither $$L$$ nor $$\overline L $$ is recursive enumerable
2
GATE CSE 2003
MCQ (Single Correct Answer)
+1
-0.3
Nobody knows yet if $$P=NP$$. Consider the language $$L$$ defined as follows
$$L = \left\{ {\matrix{ {{{\left( {0 + 1} \right)}^ * }\,\,\,if\,\,P = NP} \cr {\,\,\,\,\,\,\,\phi \,\,\,\,Otherwise} \cr } } \right.$$

Which of the following statement is true?

A
$$L$$ is recursive
B
$$L$$ is recursively enumerable but not recursive
C
$$L$$ is not recursively enumerable
D
Whether $$L$$ is recursive or not will be known after we find out if $$P=NP.$$
3
GATE CSE 2003
MCQ (Single Correct Answer)
+1
-0.3
If the strings of a language $$L$$ can be effectively enumerated in lexicographic (i.e., alphabetic$$(c)$$ order, which of the following statements is true?
A
$$L$$ is necessarily finite
B
$$L$$ is regular but not necessarily finite
C
$$L$$ is context free but not necessarily regular
D
$$L$$ is recursive but not necessarily context free
4
GATE CSE 2003
MCQ (Single Correct Answer)
+2
-0.6
Consider the following deterministic finite state automation $$M.$$ GATE CSE 2003 Theory of Computation - Finite Automata and Regular Language Question 49 English

Let $$S$$ denote the set of seven bit binary strings in which the first, the fourth, and the last bits are $$1$$. The number of strings in $$S$$ that are accepted by $$M$$ is

A
$$1$$
B
$$5$$
C
$$7$$
D
$$8$$