Gate IT 2007

Question 41

The line T in the following figure is permanently connected to the ground. Which of the following inputs (X1 X2 X3 X4) will detect the fault ?

• 0000
• 0111
• 1111
• None of these

Question 42

The two grammars given below generate a language over the alphabet {x, y, z}

Which one of the following choices describes the properties satisfied by the strings in these languages?

• G1 : No y appears before any x
  G2 : Every x is followed by at least one y
• G1 : No y appears before any x
  G2 : No x appears before any y
• G1 : No y appears after any x
  G2 : Every x is followed by at least one y
• G1 : No y appears after any x
  G2 : Every y is followed by at least one x

Question 43

Consider the following DFA in which s0 is the start state and s1, s3 are the final states.

What language does this DFA recognize ?

• All strings of x and y
• All strings of x and y which have either even number of x and even number of y or odd number or x and odd number of y
• All strings of x and y which have equal number of x and y
• All strings of x and y with either even number of x and odd number of y or odd number of x and even number of y

Question 44

Consider the grammar given below
S → x B | y A
A → x | x S | y A A
B → y | y S | y B B
Consider the following strings.
(i) xxyyx
(ii) xxyyxy
(iii) xyxy
(iv) yxxy
(v) yxx
(vi) xyx
Which of the above strings are generated by the grammar ?

• (i), (ii), and (iii)
• (ii), (v), and (vi)
• (ii), (iii), and (iv)
• (i), (iii), and (iv)

Question 45

Consider the following grammars. Names representing terminals have been specified in capital letters.

Which one of the following statements is true?

• G₁ is context-free but not regular and G₂ is regular
• G₂ is context-free but not regular and G₁ is regular
• Both G₁ and G₂ are regular
• Both G₁ and G₂ are context-free but neither of them is regular

Question 46

Consider the following finite automata P and Q over the alphabet {a, b, c}. The start states are indicated by a double arrow and final states are indicated by a double circle. Let the languages recognized by them be denoted by L(P) and L(Q) respectively.

The automation which recognizes the language L(P) ∩ L(Q) is :

• a
• b
• c
• d

Question 47

In the simplified flowchart given below, the shaded boxes represent code that is executed during a test case.

The Branch coverage is

• 3/4
• 2/3
• 1/2
• 3/8

Question 48

Consider the CPM activity chart where an arc connecting two milestones is labeled with a task identifier and the time taken in days. For example in order to go from A to B, task T1 takes 180 days. A dashed line depicts an additional dependency that is equivalent to a zero time task.

The set of activities that lie on the critical path are

• T1, T2, T8, T10
• T1, T3, T8, T10
• T1, T2, T3, T4, T5, T6, T7, T8, T9, T10
• T1, T4, T5, T7, T8, T10

Question 49

Consider the following pseudo-code:

C

 IF ((A > B) AND (C > D)) THEN
       A = A + 1
       B = B + 1
ENDIF

The cyclomatic complexity of the pseudo-code is

• 2
• 3
• 4
• 5

Question 50

Synchronization in the classical readers and writers problem can be achieved through use of semaphores. In the following incomplete code for readers-writers problem, two binary semaphores mutex and wrt are used to obtain synchronization

wait (wrt)
writing is performed
signal (wrt)
wait (mutex)  
readcount = readcount + 1
if readcount = 1 then S1
S2
reading is performed
S3
readcount = readcount - 1
if readcount = 0 then S4 
signal (mutex)

The values of S1, S2, S3, S4, (in that order) are

• signal (mutex), wait (wrt), signal (wrt), wait (mutex)
• signal (wrt), signal (mutex), wait (mutex), wait (wrt)
• wait (wrt), signal (mutex), wait (mutex), signal (wrt)
• signal (mutex), wait (mutex), signal (mutex), wait (mutex)