GATE-CS-2016 (Set 1)

Question 51

Consider the following context-free grammars: 

Which one of the following pairs of languages is generated by G1 and G2, respectively 

• A
  

• B
  

• C
  

• D
  

Question 52

Consider the transition diagram of a PDA given below with input alphabet ∑ = {a, b}and stack alphabet Γ = {X, Z}. Z is the initial stack symbol. Let L denote the language accepted by the PDA.

• A
• B
• C
• D

Question 53

Let X be a recursive language and Y be a recursively enumerable but not recursive language. Let W and Z be two languages such that Y\' reduces to W, and Z reduces to X\' (reduction means the standard many-one reduction). Which one of the following statements is TRUE

• W can be recursively enumerable and Z is recursive.
• W an be recursive and Z is recursively enumerable.
• W is not recursively enumerable and Z is recursive.
• W is not recursively enumerable and Z is not recursive

Question 54

The attributes of three arithmetic operators in some programming language are given below.

Operator  Precedence   Associativity     Arity
+           High         Left            Binary
-           Medium       Right           Binary 
*           Low          Left            Binary 

The value of the expression 2 - 5 + 1 - 7 * 3 in this language is __________ ?   Note : This question was asked as Numerical Answer Type.

• 1
• 2
• 3
• 9

Question 55

Consider the following Syntax Directed Translation Scheme (SDTS), with non-terminals {S, A} and terminals {a, b}}. Using the above SDTS, the output printed by a bottom-up parser, for the input aab is

• 1 3 2
• 2 2 3
• 2 3 1
• Syntax Error

Question 56

Consider a computer system with 40-bit virtual addressing and page size of sixteen kilobytes. If the computer system has a one-level page table per process and each page table entry requires 48 bits, then the size of the per-process page table is _________megabytes.   Note : This question was asked as Numerical Answer Type.

• 384
• 48
• 192
• 96

Question 57

Consider a disk queue with requests for I/O to blocks on cylinders 47, 38, 121, 191, 87, 11, 92, 10. The C-LOOK scheduling algorithm is used. The head is initially at cylinder number 63, moving towards larger cylinder numbers on its servicing pass. The cylinders are numbered from 0 to 199. The total head movement (in number of cylinders) incurred while servicing these requests is:   Note : This question was asked as Numerical Answer Type.

• 346
• 165
• 154
• 173

Question 58

Consider a computer system with ten physical page frames. The system is provided with an access sequence a1, a2, ..., a20, a1, a2, ..., a20), where each ai number. The difference in the number of page faults between the last-in-first-out page replacement policy and the optimal page replacement policy is __________ [Note that this question was originally Fill-in-the-Blanks question]

• 0
• 1
• 2
• 3

Question 59

Consider the following two phase locking protocol. Suppose a transaction T accesses (for read or write operations), a certain set of objects {O1,...,Ok}. This is done in the following manner: Step 1. T acquires exclusive locks to O1, . . . , Ok in increasing order of their addresses. Step 2. The required operations are performed. Step 3. All locks are released. This protocol will

• guarantee serializability and deadlock-freedom
• guarantee neither serializability nor deadlock-freedom
• guarantee serializability but not deadlock-freedom
• guarantee deadlock-freedom but not serializability

Question 60

Consider that B wants to send a message m that is digitally signed to A. Let the pair of private and public keys for A and B be denoted represent the operation of encrypting m with a key Kx and H(m) represent the message digest. Which one of the following indicates the CORRECT way of sending the message m along with the digital signature to A?

• A
• B
• C
• D