Monday, 8 June 2020

UGC NET Computer Science December 2019 | Question 1

Question 1

Which of the learning outcomes are intended in teaching organized at understanding level?

1. Longer recall and retention of facts
2. Seeking of relationships and patterns among facts
3. Creative construction and critical interpretation of ideas
4. Mastery of facts and information

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UGC NET CS December 2019 - Question 1	UGC NET CS Dec 2019 - Question 2

Wednesday, 3 June 2020

UGC NET Computer Science December 2019 | Question 145

Question 145

A flow graph F with entry node (1) and exit node (11) is shown below:

How many predicate nodes are there and what are their names?

1. Three : (1, (2, 3), 6)
2. Three: (1, 4, 6)
3. Four : ((2, 3), 6, 10, 11)
4. Four: ((2, 3), 6, 9, 10)

Answer : 1. Three : (1, (2, 3), 6)

Explanation Question 145

Predicate is a node that contains condition. It means at least 2 outgoing edges required to qualify as a predicate.
Total number of predicates are THREE.

The vertex 1 is contains 2 outgoing edges are (2,3) and 11
The vertex (2,3) contains 2 outgoing edges are 6 and (4,5)
The vertex 6 contains 2 outgoing edges are 7 and 8.

So, option 1 is correct answer

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UGC NET CS December 2019 - Question 144	UGC NET CS December 2019 - Question 146

UGC NET Computer Science December 2019 | Question 122

Question 122

Which of the following are legal statements in C programming language?
(a) int * P= &44 ;
(b) int * P= &r ;
(c) int P= &a ;
(d) int P= a ;
Choose the correct option :

1. (a) and (b)
2. (b) and (c)
3. (b) and (d)
4. (a) and (d)

Answer : 3. (b) and (d)

Explanation Question 122

Legal Statements:

int *P = &r; Here, Pointer variable P is storing address of variable r.
int P = a; Here, P will hold value assigned by a.

Illegal Statements:

int *P = &44; Here, Pointer variable is storing address of number. This is not legal statement. First its needed to assign the value 44 in some variable and then address of that variable can stored by Pointer variable P.
int P = &a; Here, P variable trying to store the address of the variable. It's illegal. It should be pointer in place of the int P variable.

So, option 3 is correct answer

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UGC NET CS December 2019 - Question 121	UGC NET CS December 2019 - Question 123

UGC NET Computer Science December 2019 | Question 142

Question 142

A flow graph F with entry node (1) and exit node (11) is shown below:

What is the cyclomatic complexity of flowgraph F?

1. 2
2. 3
3. 4
4. 3

Answer : 3. 4

Explanation Question 142

To find cyclomatic complexity we have 3 formulas

The number of regions(R) corresponds to the cyclomatic complexity. Total number of regions(R) are 4.
V(G), Flow graph is defined as V(G) = P + 1 where p is the number of predicate nodes contained in the flow graph G. Predicates are 3 + 1 = 4
V(G), Flow graph is defined as V(G) = E - N + 2 where E is the number of flow graph edges, and N is the number of flow graph nodes.
Edges(E) - Nodes(N) + 2
= 11 - 9 + 2
= 2 + 2
= 4

So, option 3 is correct answer

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UGC NET CS December 2019 - Question 141	UGC NET CS December 2019 - Question 143

UGC NET Computer Science December 2019 | Question 141

Question 141

A flow graph F with entry node (1) and exit node (11) is shown below:

Add caption

How many nodes are there in flowgraph F?

1. 9
2. 10
3. 11
4. 12

Answer : 1. 9

Explanation Question 141

Above graph contains 9 nodes and 11 edges.
The nodes are nothing but vertices.
Here, In above given diagram the number of rounds are the nodes
The nodes are 1, (2,3), (4,5), 6, 7, 8, 9, 10, 11.
Count of total nodes in flowgraph F are 9.

So, option 1 is correct answer

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UGC NET CS December 2019 - Question 140	UGC NET CS December 2019 - Question 142

UGC NET Computer Science December 2019 | Question 133

Question 133

According to the ISO-9126 Standard Quality Model. match the attributes given in List-I with their definitions in List-II :

List I	List II
a. Functionality	i. Relationship between level of performance and amount of resources
b. Reliability	ii. Characteristics related with achievement of purpose
c. Efficiency	iii. Effort needed to make for improvement
d. Maintainability	iv. Capability of software to maintain

Choose the correct option from the ones given below :

1. (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
2. (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
3. (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)
4. (a)-(i), (b)-(ii), (c)-(iv), (d)-(iii)

Answer : 3. (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)

Explanation Question 133

6 main quality characteristics for ISO-9126 Standard Quality Model:

Functionality→ Characteristics related with achievement of purpose
Reliability → Capability of software to maintain performance of software
Efficiency → Relationship between level of performance and amount of resources
Maintainability → Effort needed to make for improvement
Usability → Usability only exists with regard to functionality and refers to the ease of use for a given function.
Portability → This characteristic refers to how well the software can adapt to changes in its environment or with its requirements.

Reference : ISO/IEC 9126

So, option 3 is correct answer

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UGC NET CS December 2019 - Question 132	UGC NET CS December 2019 - Question 134

UGC NET Computer Science December 2019 | Question 143

Question 143

A flow graph F with entry node (1) and exit node (11) is shown below:

How many regions are there in flowgraph F?

1. 2
2. 3
3. 4
4. 8

Answer :

Explanation Question 143

The region is nothing but a combination of closed region and outer region. Any graph must have one outer region.
Here, 3 closed regions are available and one outer region is available.

Closed 3 regions are:

Closed region by nodes → 1, (2, 3), (4, 5) and 10
Closed region by nodes → 6, 7, 8, 9
Closed region by nodes → (2, 3), 6, 7, 8, 9, 10 and (4, 5)

One outer region.

So, the total number of regions are 4.

So, option 3 is correct answer

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UGC NET CS December 2019 - Question 142	UGC NET CS December 2019 - Question 144

UGC NET Computer Science December 2019 | Question 123

Question 123
Two concurrent executing transactions T1 and T2 are allowed to update same stock item say 'A' in an uncontrolled manner. In such scenario. following problems may occur :
(a) Dirty read problem
(b) Lost update problem
(c) Transaction failure
(d) Inconsistent database state
Which of the following option is correct if database system has no concurrency module and allows concurrent execution of above two transactions?

1. (a), (b) and (c) only
2. (c) and (d) only
3. (a) and (b) only
4. (a), (b) and (d) only

Answer : 4. (a), (b) and (d) only

Explanation Question 123

Following problems can occur when concurrent transactions execute in an uncontrolled manner:

The Lost Update Problem. When two transactions access the same database items and also perform their own operations in a way that makes the value of some database item wrong, a lost update problem takes place.
Uncommitted Dependency - Dirty Read Problem(or Temporary Update Problem). A dirty read problem occurs when a transaction updates an item in the database and then there is a failure in the transaction for some reason. As the transaction fails, the updated item in the database is accessed by another transaction before it can go back to the original value.
The Incorrect Summary Problem. If one transaction is calculating an aggregate summary function on a number of database items while other transactions are updating some of these items, the aggregate function may calculate some values before they are updated and others after they are updated.
The Unrepeatable Read Problem. Another problem that may occur is called unrepeatable read, where a transaction T reads the same item twice and the item is changed by another transaction T between the two reads. Hence, T receives different values for its two reads of the same item.
Phantom Read Problem

The Unrepeatable Read Problem Example
Suppose two users X and Y access a department’s database concurrently. User X is updates the database to provide all employees with a salary raise of 5%. At the same time, user Y wants to know the total salary that has been paid to the department.
As the two transactions are being executed simultaneously on the same database, there is always a high probability to interfere with each other. As a result, the sum includes certain salaries before the raise and certain salaries subsequent to the raise. Such a sum cannot be considered as an acceptable value of the total salary (the value before the raise or after the raise would be different)

Reference 1 : Concurrency problems in DBMS Transactions

Reference 1 : Concurrency Anomalies - Incorrect Summary Problem

From above we can conclude that only options (a), (b) and (d) can be included in problems whoch can occur when concurrent transactions execute in an uncontrolled manner.

So, option 4 is correct answer

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UGC NET CS December 2019 - Question 122	UGC NET CS December 2019 - Question 124

UGC NET Computer Science December 2019 | Question 124

Question 124

Identify the circumstances under which preemptive CPU scheduling is used :
(a) A process switches from Running state to Ready state
(b) A process switches from Waiting state to Ready state
(c) A process completes its execution
(d) A process switches from Ready to Waiting state
Choose the correct option :

1. (a) and (b) only
2. (a) and (d) only
3. (c) and (d) only
4. (a), (b), (c) only

Answer : 1. (a) and (b) only

Explanation Question 124

Preemptive Scheduling According to Standard book of Galvin,
CPU scheduling decisions take place under one of four conditions:

When a process switches from the running state to the waiting state, such as for an I/O request or invocation of the wait( ) system call.
When a process switches from the running state to the ready state, for example in response to an interrupt.
When a process switches from the waiting state to the ready state, say at completion of I/O or a return from wait( ).
When a process terminates.

For conditions 1 and 4 there is no choice - A new process must be selected.
For conditions 2 and 3 there is a choice - To either continue running the current process, or select a different one.
If scheduling takes place only under conditions 1 and 4, the system is said to be non-preemptive, or cooperative. Under these conditions, once a process starts running it keeps running, until it either voluntarily blocks or until it finishes. Otherwise the system is said to be preemptive.

In above discussion. it's given that If scheduling takes place only under conditions 1 and 4, the system is said to be non-preemptive. Otherwise the system is said to be preemptive. Therefore point 2 & 3 are condition for preemptive system.

Here point 2 and 3 are as listed below

When a process switches from the running state to the ready state.
When a process switches from the waiting state to the ready state.

These above point matches with circumstances (a) & (b) given in question.

So, option 1 is correct answer

Reference 1 : CPU Scheduling - Preemptive Scheduling

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UGC NET CS December 2019 - Question 123	UGC NET CS December 2019 - Question 125

UGC NET Computer Science December 2019 | Question 125

Question 125
The following multithreaded algorithm computes transpose of a matrix in parallel: p Trans (X, Y, N)
if N=1
then Y [1,1] ← X[1,1]
else partition X into four (N/2)x (N/2) submatrices X11,X12,X21,X22
partition Y into four (N/2)x(N/2) submatrices Y11,Y12,Y21,Y22.
spawn p Trans (X11,Y11,N/2)
spawn p Trans (X12,Y12,N/2)
spawn p Trans (X21,Y21,N/2)
spawn p Trans (X22,Y22,N/2)
What is the asymptotic parallelism of the algorithm?

1. T₁/T_∞ or θ(N² / lg N)
2. T₁/T_∞ or θ(N / lg N)
3. T₁/T_∞ or θ(lg N / N²)
4. T₁/T_∞ orθ(lg N/ N)

Answer : 1. T₁/T_∞ or θ(N² / lg N)

Explanation Question 125

Option 1 is correct answer

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UGC NET CS December 2019 - Question 124	UGC NET CS December 2019 - Question 126

UGC NET Computer Science December 2019 | Question 126

Question 126
Consider the following statements :
(a) The running time of dynamic programming algorithm is always θ(ρ) where ρ is number of subproblems.
(b) When a recurrence relation has cyclic dependency, it is impossible to use that recurrence relation (unmodified) in a correct dynamic program.
(c) For a dynamic programming algorithm, computing all values in a bottom-up fashion is asymptotically faster than using recursion and memorization.
(d) If a problem X can be reduced to a known NP-hard problem. then X must be NP-hard
Which of the statement(s) is (are) true?

1. Only (b) and (a)
2. Only (b)
3. Only (b) and (c)
4. Only (b) and (d)

Answer : 2. Only (b)

Explanation Question 126

The running time of a dynamic program is the number of subproblems times the time per subproblem. This would only be true if the time per subproblem is O(1). False
Cyclic dependency is a relation between two or more modules which either directly or indirectly depend on each other to function properly. Such modules are also known as mutually recursive. So, we can’t get correct solution when we are using dynamic programming. True
A bottom up implementation must go through all of the sub-problems and spend the time per subproblem for each. Using recursion and memoization only spends time on the subproblems that it needs. In fact, the reverse may be true: using recursion and memoization may be asymptotically faster then a bottom-up implementation. False
If a problem X can be reduced to a known NP-hard problem, then X must be NP-Complete. False

Hence, statement b is the only true.

So, option 2 is correct answer

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UGC NET CS December 2019 - Question 125	UGC NET CS December 2019 - Question 127

UGC NET Computer Science December 2019 | Question 127

Question 127

Consider the following statements :
(a) Fiber optic cable is much lighter than copper cable.
(b) Fiber optic cable is not affected by power surges or electromagnetic interference.
(c) Optical transmission is inherently bidirectional.
Which of the statements is (are) correct?

1. Only (a) and (b)
2. Only (a) and (c)
3. Only (b) and (c)
4. (a), (b) and (c)

Answer : 1. Only (a) and (b)

Explanation Question 127

Fiber optic cable is much lighter than copper cable. True
Fiber optic cable is not affected by power surges or electromagnetic interference. True
Optical transmission is inherently bidirectional. False

Given statement (c) is false because bidirectional Fiber Optics can be implemented with by WDM (Wavelength-division multiplexing) or by rearranging two unidirectional Fibers, its not inherently bidirectional.

Only given options (a) and (b) are correct statements on Fibre optics.

So, option 1 is correct answer

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UGC NET CS December 2019 - Question 126	UGC NET CS December 2019 - Question 128

UGC NET Computer Science December 2019 | Question 128

Question 128
Consider the following statements :
(a) Windows Azure is a cloud-based operating system.
(b) Google App Engine is an integrated set of online services for consumers to communicate and share with others.
(c) Amazon Cloud Front is a web service for content delivery.
Which of the statements is (are) correct?

1. Only (a) and (b)
2. Only (a) and (c)
3. Only (b) and (c)
4. (a), (b) and (c)

Answer : 2. Only (a) and (c)

Explanation Question 128

Windows Azure is a cloud-based operating system. True
Google App Engine is an integrated set of online services for consumers to communicate and share with others. False
Amazon Cloud Front is a web service for content delivery. True

Microsoft Azure, commonly referred to as Azure, is a cloud computing service created by Microsoft for building, testing, deploying, and managing applications and services through Microsoft-managed data centers.

Google App Engine (often referred to as GAE or simply App Engine) is a Platform as a Service and cloud computing platform for developing and hosting web applications in Google-managed data centers.

Amazon CloudFront is a content delivery network (CDN) offered by Amazon Web Services. Content delivery networks provide a globally-distributed network of proxy servers which cache content, such as web videos or other bulky media, more locally to consumers, thus improving access speed for downloading the content.

Statement (b) is wrong because Google App Engine is a cloud computing platform for developing and hosting web applications in Google-managed data centers. It's not an online services for consumers to communicate and share with others.

Hence, Correct statements are only (a) and (c)

So, option 2 is correct answer

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UGC NET CS December 2019 - Question 127	UGC NET CS December 2019 - Question 129

UGC NET Computer Science December 2019 | Question 129

Question 129

Consider the following statements with respect to network security :
(a) Message confidentiality means that the sender and the receiver expect privacy.
(b) Message integrity means that the data must arrive at the receiver exactly as they were sent.
(c) Message authentication means the receiver is ensured that the message is coming from the intended sender.
Which of the statements is (are) correct?

1. Only (a) and (b)
2. Only (a) and (c)
3. Only (b) and (c)
4. (a), (b) and (c)

Answer : 4. (a), (b) and (c)

Explanation Question 129

Message Confidentiality
In information security, confidentiality "is the property, that information is not made available or disclosed to unauthorized individuals, entities, or processes." Confidentiality is a component of privacy that implements to protect our data from unauthorized viewers. Examples of confidentiality of electronic data being compromised include laptop theft, password theft, or sensitive emails being sent to the incorrect individuals.

Message Integrity
This means that data cannot be modified in an unauthorized or undetected manner.

Message Authentication
Authentication is the act of verifying a claim of identity.

References:

All three statements are correct.

So, option 4 is correct answer

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UGC NET CS December 2019 - Question 128	UGC NET CS December 2019 - Question 130

UGC NET Computer Science December 2019 | Question 130

Question 130
Consider the following :
(a) Trapping at local maxima
(b) Reaching a plateau
(c) Traversal along the ridge.
Which of the following option represents shortcomings of the hill climbing algorithm?

1. (a) and (b) only
2. (a) and (c) only
3. (b) and (c) only
4. (a), (b) and (c)

Answer : 4. (a), (b) and (c)

Explanation Question 108

Problems in Hill Climbing Algorithm:

Local Maximum: A local maximum is a peak state in the landscape which is better than each of its neighboring states, but there is another state also present which is higher than the local maximum.
Solution: Backtracking technique can be a solution of the local maximum in state space landscape. Create a list of the promising path so that the algorithm can backtrack the search space and explore other paths as well.
Plateau: A plateau is the flat area of the search space in which all the neighbor states of the current state contains the same value, because of this algorithm does not find any best direction to move. A hill-climbing search might be lost in the plateau area.
Solution: The solution for the plateau is to take big steps or very little steps while searching, to solve the problem. Make a big jump. Randomly select a state far away from the current state. Chances are that we will land at a non-plateau region
Ridges: A ridge is a special form of the local maximum. It has an area which is higher than its surrounding areas, but itself has a slope, and cannot be reached in a single move.
Solution: With the use of bidirectional search, or by moving in different directions, we can improve this problem.

Reference 1 : Problems in Hill Climbing Algorithm in AI

(a), (b), (c) all are shortcomings of the hill climbing algorithm.

So, option 4 is correct answer

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UGC NET CS December 2019 - Question 129	UGC NET CS December 2019 - Question 131

UGC NET Computer Science December 2019 | Question 132

Question 132

Match List-I and List-II:

List - I	List - II
a. Physical layer	i. Provide token management service
b. Transport Layer	ii. Concerned with transmitting raw bits over a communication channel
c. Session layer	iii. Concerned with the syntax and semantics of the information transmitted
d. Presentation layer	iv. True end-to-end layer from source to destination

Choose the correct option from those given below :

1. (a)-(ii), (b)-(iv), (c)-(iii), (d)-(i)
2. (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)
3. (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)
4. (a)-(iv), (b)-(ii), (c)-(i), (d)-(iii)

Answer : 3. (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)

Explanation Question 132

Physical layer → Concerned with transmitting raw bits over a communication channel
Transport layer → True end-to-end layer from source to destination
Session layer → Provide token management service
Presentation layer → Concerned with the syntax and semantics of the information transmitted

So, option 3 is correct answer

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UGC NET CS December 2019 - Question 131	UGC NET CS December 2019 - Question 133

UGC NET Computer Science December 2019 | Question 134

Question 134

Match the Agile Process models with the task performed during the model :

List I	List II
a. Scrum	i. CRC cards
b. Adaptive software development	ii. Sprint backlog
c. Extreme programming	iii. <action> the <result> <by/for/of/to> a(n) <object>
d. Feature-driven development	iv. Time box release plan

Choose the correct option from those given below :

1. (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)
2. (a)-(i), (b)-(iii), (c)-(ii), (d)-(iv)
3. (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
4. (a)-(i), (b)-(iv), (c)-(ii), (d)-(iii)

Answer : 1. (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)

Explanation Question 134

Scrum → Sprint backlog
Adaptive software development → Time box release plan
Extreme programming → CRC cards
Feature-driven development → <action> the <result> <by/for/of/to> a(n) <object>

So, option 1 is correct answer

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UGC NET CS December 2019 - Question 133	UGC NET CS December 2019 - Question 135

UGC NET Computer Science December 2019 | Question 135

Question 135

Match List-I with List-II :

List I	List II
a. Frame attribute	i. to create ink in HTML
b. <tr> tag	ii. for vertical alignment of content in cell
c. Valign attribute	iii. to enclose each row in table
d. <a> tag	iv. to specify the side of the table frame that display border

Choose the correct option from those given below :

1. (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
2. (a)-(ii), (b)-(i), (c)-(iii), (d)-(iv)
3. (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)
4. (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)

Answer : 3. (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)

Explanation Question 135

Frame attribute → To specify the side of the table frame that display border. The < frame > tag defines one particular window (frame) within a <frameset>. Each < frame > in a < frameset > can have different attributes, such as border, scrolling, the ability to resize, etc.
< tr > tag → To enclose each row in a table.The < tr > tag defines a row in an HTML table.A < tr > element contains one or more or elements
Valign attribute → for vertical alignment of content in cell
< a > tag → To create link in HTML

So, option 3 is correct answer

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UGC NET CS December 2019 - Question 134	UGC NET CS December 2019 - Question 136

UGC NET Computer Science December 2019 | Question 136

Question 136

An instruction is stored at location 500 with its address field at location 501. The address field has the value 400. A processor register R₁ contains the number 200. Match the addressing mode (List-I) given below with effective address (List-II) for the given instruction:

Match List-I with List-II :

List I	List II
a. Direct	i. 200
b. Register indirect	ii. 902
c. Index with R1 as the index register	iii. 400
d. Relative	iv. 600

1. (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)
2. (a)-(i), (b)-(ii)), (c)-(iii), (d)-(iv)
3. (a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)
4. (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)

Answer : 1. (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)

Explanation Question 136

				Main Memory
Instruction			500	Opcode	Mode
Opcode	500	→	501
			502	Next Instruction
			⋮
	R₁	200	⋮
			⋮ ⋮

Direct Address = 400
Relative Address = Next Instruction memory location + Direct Address value
= 502 + 400
= 902

Register indirect Address= 200
Indexed Address = Register Indirect Address + Direct Address
= 200 + 400
= 600

So, option 1 is correct answer

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UGC NET CS December 2019 - Question 135	UGC NET CS December 2019 - Question 137

UGC NET Computer Science December 2019 | Question 137

Question 137

Match List-I and List-II :

List I	List II
a. Isolated I/O	i. same set of control signal for I/O and memory communication
b. Memory mapped I/O	ii. separate instructions for I/O and memory communication
c. I/O interface	iii. requires control signals to be transmitted between the communicating units
d. Asynchronous data transfer	iv. resolve the differences in central computer and peripherals

Choose the correct option from those given below :

1. (a)-(ii), (b)-(iii), (c)- (iv), (d)-(i)
2. (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
3. (a)-(iii), (b)-(i), (c)-(iv), (d)-(iii)
4. (a)-(i), (b)-(ii), (c)-(iv), (d)-(iii)

Answer : 3. (a)-(iii), (b)-(i), (c)-(iv), (d)-(iii)

Explanation Question 137

Isolated I/O → Separate instructions for I/O and memory communication
Memory mapped I/O → Same set of control signal for I/O and memory communication
I/O interface → Resolve the differences in central computer and peripherals
Asynchronous data transfer → Requires control signals to be transmitted between the communicating units

So, option 3 is correct answer

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UGC NET CS December 2019 - Question 136	UGC NET CS December 2019 - Question 138

UGC NET Computer Science December 2019 | Question 138

Question 138

Match List-I with List-II :

List I	List II
(a) Micro operation	(i) Specify micro operations
(b) Micro programmed control unit	(ii) Improve CPU utilization
(c) Interrupts	(iii) Control Memory
(d) Micro instruction	(iv) Elementary operation performed on data stored in registers

Choose the correct option from those given below:

1. (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)
2. (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)
3. (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
4. (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)

Answer : 1. (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)

Explanation Question 138

Micro operation → Elementary operation performed on data stored in registers
Micro programmed control unit → Control Memory
Interrupts → Improve CPU utilization
Micro instruction → Specify micro operations

So, option 1 is correct answer

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UGC NET CS December 2019 - Question 137	UGC NET CS December 2019 - Question 139

UGC NET Computer Science December 2019 | Question 139

Question 139

Weather Information System

The sequence diagram given in Figure 1 for the Weather Information System takes place when an external system requests the summarized data from the weather station. The increasing order of lifeline for the objects in the system are:

1. Sat comms → Weather station → Commslink → Weather data
2. Sat comms → Comms link → Weather station → Weather data
3. Weather data → Comms link → Weather station → Sat Comms
4. Weather data → Weather station → Comms link > Sat Comms
5. Question remains cancelled

Answer : 5. Question remains cancelled

Explanation Question 139

According to given UGC NET final key, question remains cancelled and marks awarded to all Page 1 candidates appeared in the test.

A connection is established in order to send and receive data between sender and receiver. And a link is disconnect after completion of data transfer.

Given diagram, Sat Comms requests data to whether station, whether station requests data to Comms link and comm link requests data from whether data.

Comm link gets data first from whether data then the link between comm link and whether data is smallest. Similarly lifetime if connection between Sat comms and whether station is largest.

Hence the increasing order of lifeline for the objects in the system are Weather data → Comms link → Weather station → Sat Comms.

Note: Most appropriate answer is option-C.

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UGC NET CS December 2019 - Question 138	UGC NET CS December 2019 - Question 140

UGC NET Computer Science December 2019 | Question 140

Question 140

The Data Encryption Standard (DES) has a function consists of four steps. Which of the following is correct order of these four steps?

1. an expansion permutation, S-boxes, an XOR operation, a straight permutation
2. an expansion permutation, an XOR operation, S-boxes, a straight permutation
3. a straight permutation, S-boxes, an XOR operation, an expansion permutation
4. a straight permutation, an XOR operation, S-boxes, an expansion permutation

Answer : 2. an expansion permutation, an XOR operation, S-boxes, a straight permutation

Explanation Question 140

Reference : Data Encryption Standard - Round Function

Steps inside DES Round Function are an expansion permutation, an XOR operation, S-boxes, a straight permutation.

So, option 2 is correct answer

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UGC NET CS December 2019 - Question 139	UGC NET CS December 2019 - Question 141

UGC NET Computer Science December 2019 | Question 144

Question 144

A flow graph F with entry node (1) and exit node (11) is shown below:

How many nodes are there in the longest independent path?

1. 6
2. 7
3. 8
4. 9

Answer : 3. 8

Explanation Question 144

The longest independent path nodes are 8 but it have 2 possibilities
Path 1: 1 → (2,3) → 6 → 7 → 9 → 10 → 1 → 11
(or)
Path 2: 1 → (2,3) → 6 → 8 → 9 → 10 → 1 → 11

So, option 3 is correct answer

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UGC NET CS December 2019 - Question 143	UGC NET CS December 2019 - Question 145

UGC NET Computer Science December 2019 | Question 146

Question 146

Comprehension:
Answer question (146-150) based on the problem statement given below:
An organization needs to maintain database having five attributes A, B, C, D, E.
These attributes are functionally dependent on each other for which functionally dependency set F is given as :
F : { A → BC, D → E, BC → D, A → D }.
Consider a universal relation R(A, B, C, D, E) with functional dependency set F.
Also all attributes are simple and take atomic values only.

Minimal cover F' of functional dependency set F is

1. F'= { A → B, A → C, BC → D, D → E }
2. F'= { A → BC, B → D, D → E }
3. F'= { A → B, A → C, A → D, D → E }
4. F'= { A → B, A → C, B → D, C → D, D → E }

Answer : 1. F'= { A → B, A → C, BC → D, D → E }

Explanation Question 146

Steps to find minimal cover:
Step 1: Write all FDs in such a way that the RHS of each FD contain only single attribute.
A → B
A → C
D → E
BC → D
A →D

Step 2: Then for each FD see whether that RHS attribute can be driven by the LHS attribute using any other remaining FDs, if yes then remove that FD otherwise keep it. Here, below dependency A →D
can be derived by usign other dependencies A → BC and BC → D. hence, we remove dependency A → D. So step 1 results in following FDs:
A → B
A → C
D → E
BC → D

Step 3: Now see the FD which is having 2 or more attributes in its LHS.Then find the closure of LHS attributes and then eliminate the attributes from LHS which are common in clsure. Above BC are two attributes in LHS.
B⁺ = {B}
C⁺ = {C}
Since nothing is common in closure so keep both attributes in LHS.
Hence minimal cover is
A → B
A → C
D → E
BC → D

So, option 1 is correct answer

Simple properties/steps of minimal cover:

Right Hand Side (RHS) of all FDs should be single attribute.
Remove extraneous attributes.
Eliminate redundant functional dependencies.

Reference Example : Find minimal cover of set of functional dependencies Exercise

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UGC NET CS December 2019 - Question 145	UGC NET CS December 2019 - Question 147

UGC NET Computer Science December 2019 | Question 147

Question 147

Comprehension:
Answer question (146-150) based on the problem statement given below:
An organization needs to maintain database having five attributes A, B, C, D, E.
These attributes are functionally dependent on each other for which functionally dependency set F is given as :
F : { A → BC, D → E, BC → D, A → D }.
Consider a universal relation R(A, B, C, D, E) with functional dependency set F.
Also all attributes are simple and take atomic values only.

Identify primary key of table R with functional dependency set F

1. BC
2. AD
3. A
4. AB

Answer : 3. A

Explanation Question 147

Since "A" is not in RHS of any FD
So, "A" is the key of relation R.
Now to see whether "A" is the primary key or not of relation “R”.
lets find closure of "A".
A⁺ = { A, B, C, D, E }.
Hence A is the primary key of relation R

So, option 3 is correct answer

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UGC NET CS December 2019 - Question 146	UGC NET CS December 2019 - Question 148

UGC NET Computer Science December 2019 | Question 148

Question 148

Comprehension:
Answer question (146-150) based on the problem statement given below:
An organization needs to maintain database having five attributes A, B, C, D, E.
These attributes are functionally dependent on each other for which functionally dependency set F is given as :
F : { A → BC, D → E, BC → D, A → D }.
Consider a universal relation R(A, B, C, D, E) with functional dependency set F.
Also all attributes are simple and take atomic values only.

Identify the normal form in which relation R belong to

1. 1 NF
2. 2 NF
3. 3 NF
4. BCNF

Answer : 2. 2 NF

Explanation Question 148

Since "A" is the primary key or "R" and there is no partial dependency So "R" is in 2NF.

Since, D → E, BC → D neither have a super key in their LHS nor a prime key attribute in their RHS so "R" is not in 3NF.

Since "R" is not in 3NF it can’t be in BCNF.

So, option 2 is correct answer.

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UGC NET CS December 2019 - Question 147	UGC NET CS December 2019 - Question 149

UGC NET Computer Science December 2019 | Question 149

Question 149

Comprehension:
Answer question (146-150) based on the problem statement given below:
An organization needs to maintain database having five attributes A, B, C, D, E. These attributes are functionally dependent on each other for which functionally dependency set F is given as :
F : { A → BC, D → E, BC → D, A → D }.
Consider a universal relation R(A, B, C, D, E) with functional dependency set F. Also all attributes are simple and take atomic values only.

Identify the redundant functional dependency in F

1. BC → D
2. D→E
3. A→D
4. A→BC

Answer : 3. A → D

Explanation Question 149

A → D is redundant because A can determine D using other 2 FD's A → BC and BC → D.

So, option 3 is correct answer

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UGC NET CS December 2019 - Question 148	UGC NET CS December 2019 - Question 150

UGC NET Computer Science December 2019 | Question 150

Question 150

Comprehension:
Answer question (146-150) based on the problem statement given below:
An organization needs to maintain database having five attributes A, B, C, D, E. These attributes are functionally dependent on each other for which functionally dependency set F is given as :
F : { A → BC, D → E, BC → D, A → D }.
Consider a universal relation R(A, B, C, D, E) with functional dependency set F. Also all attributes are simple and take atomic values only.

Assume that given table R is decomposed in two tables R1(A, B, C) with functional dependency set f1 ={A → B, A → C} and R2(A, D, E) with FD set F2 ={A → D, D → E}.
Which of the following option is true w.r.t. given decomposition?

1. Dependency preservation property is followed
2. R1 and R2 are both in 2 NF
3. R1 is in 2 NF and R2 is in 3 NF
4. R1 is in 3 NF and R2 is in 2 NF

Answer : 4. R1 is in 3 NF and R2 is in 2 NF

Explanation Question 150

Since, In R1 and R2 BC can’t determine BC → D of relation "R". Hence R1 and R2 are not following the Dependency preservation property.

Candidate key of R1 is "A". And since LHS of R1 contains only "A" so R1 is in 3NF.
Candidate key of R2 is "A" , But Since D → E neither have Super key in its LHS nor have a prime key attribute in its RHS, Here it's a transitive dependency of A → D and D → E. So R2 is not in 3NF but in 2NF.

So, option 4 is correct answer

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UGC NET CS December 2019 - Question 149

UGC NET CS 2019 4 December | Question 131

Question 131
Consider the following learning algorithms :
(a) Logistic repression
(b) Back propogation
(c) Linear repression
Which of the followmg option represents classification algorithms?

1. (a) and (b) only
2. (a) and (c) only
3. (b) and (c) only
4. (a), (b) and (c)
5. Question remains cancelled

Answer : 5. Question remains cancelled

Explanation Question 131

According to UGC NET Answer key.
This question remains cancelled and marks awarded to all candidates appeared in the test.
The classification learning algorithms are

Logistic regression
Back propagation

Note : They given spelling mistake in Logistic regression and Linear Regression instead of "repression".

References :

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UGC NET CS December 2019 - Question 130	UGC NET CS December 2019 - Question 132

UGC NET Computer Science December 2019 | Question 113

Question 113
Let W_ij, represents weight between node i at layer k and node j at layer (k-1) of a given multilayer perceptron. The weight updation using gradient descent method is given by

Where α and E represents learning rate and Error in the output respectively.

1. W_ij(t+1)=W_ij(t)+α ∂E/∂W_ij , 0<=α<=1
2. W_ij(t+1)=W_ij(t)-α ∂E/∂W_ij , 0<=α<=1
3. W_ij(t+1)=α ∂E/∂W_ij , 0<=α<=1
4. W_ij(t+1)= - α ∂E/∂W_ij , 0<=α<=1

Answer : 2. Wij(t+1)=Wij(t)-α ∂E/∂Wij , 0<=α<=1

Explanation Question 113

Option 2 is correct answer

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UGC NET CS December 2019 - Question 112	UGC NET CS December 2019 - Question 114

UGC NET Computer Science December 2019 | Question 65

Question 65
Let A be the base class in C++ and B be the derived class from A with protected inheritance. Which of the following statement is false for class B?

1. Member function of class B can access protected data of class A
2. Member function of Class B can access public data of class A
3. Member function of class B cannot access private data of class A
4. Object of derived class B can access public base class data

Explanation

If protected access specifier is used while deriving class then the public and protected data members of the base class becomes the protected member of the derived class and private member of the base class are inaccessible.

In this case, the members of the base class can be used only within the derived class as protected members except for the private members.

TRUE: Member function of class B can access protected data of class A
TRUE: Member function of Class B can access public data of class A
TRUE: Member function of class B cannot access private data of class A
FALSE: Object of derived class B can access public base class data

Private and protected member variables of a derived class are not accessed by using direct member access operator

Given option 4 statement is false.

So, option 4 is correct answer

Reference with example: C++ Access Specifiers - Protected Access Specifier

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UGC NET CS December 2019 - Question 64	UGC NET CS December 2019 - Question 66

UGC NET Computer Science December 2019 | Question 66

Question 66
Which tag is used to enclose any number of javascript statements in HTML document?

1. <code>
2. <script>
3. <title>
4. <body>

Explanation

The < script > tag is used to define a client-side script (JavaScript).

The < script > element either contains scripting statements, or it points to an external script file through the src attribute.

Common uses for JavaScript are image manipulation, form validation, and dynamic changes of content.

Rest options are part of a normal HTML document.

So, option 2 is correct answer

Look at below example java script function for more detail: this function changes the html element text, style text color and fontSize. This function encloses 3 statements.



<!DOCTYPE html>

<html>

<head>

<script>

function myFunction() {

  document.getElementById("demo").innerHTML = "Hello World!";

   document.getElementById("demo").style.color = "blue";

   document.getElementById("demo").style.fontSize = "35px";

}

</script>

</head>

<body>

<p>When you click "Try it", a function will be called.</p>

<p>The function will display a message.</p>

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>

</body>

</html>

Reference : JavaScript Introduction

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UGC NET CS December 2019 - Question 65	UGC NET CS December 2019 - Question 67

UGC NET Computer Science December 2019 | Question 67

Question 67
A rectangle is bound by the lines x=0; y=0; x=5 and y=3. The line segment joining (-1, 0) and (4, 5). if clipped against this window will connect the points ______

1. (0, 1) and (3, 3)
2. (0, 1) and (2, 3)
3. (0, 1) and (4, 5)
4. (0.1) and (3, 5)

Explanation

This is simple 2-D geometry question based on equation of line (although clipping window is given and it seems to be based on Cohen Sutherland line clipping algorithm)

We have to find the two points which are the endpoint of the line segment clipped by given rectangle window. Refer the final diagram for more understanding,

Given line segment joining (−1,0) and (4,5) and lets say new endpoints of line segment after clipping are (x,y) and (x1,y1). As all these 4 points are on the same line. So, slope of the line joining any two points is same.

So, by using equation of slope of a the line,
Slope of line = (y₂ – y₁) / (x₂ - x₁)

Lets consider point (x,y).

slope of line joining (x,y) & (-1,0) = slope of line joining (4,5) & (-1,0)
∴ (y − 0) / (x − (−1)) = (5 − 0) / (4 − (−1))
∴ y = x + 1

Now only choice A (0,1) and (2,3) satisfy above equation.

So, It conclude that, points (0, 1) and (2, 3) connect line which clipped against given rectangle window.

Hence Option 2 is the right answer.

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UGC NET CS December 2019 - Question 66	UGC NET CS December 2019 - Question 68

UGC NET Computer Science December 2019 | Question 72

Question 72

Given two tables

EMPLOYEE (EID, ENAME, DEPTNO)
DEPARTMENT (DEPTNO, DEPTNAME)

Find the most appropriate statement of the given query :

Select count (*) 'total' from EMPLOYEE
where DEPTNO IN (D1, D2)
group by DEPTNO having count (*) > 5

1. Total number of employees in each department D1 and D2
2. Total number of emplovees of department D1 and D2 if their total is > 5
3. Display total number of employees in both departments D1 and D2
4. The output of the query must have atleast two rows

Answer : 2. Total number of emplovees of department D1 and D2 if their total is > 5

Explanation

Given query group by distinct DEPTNO on the EMPLOYEE relation having rows with same DEPTNO are greater than 5 (i.e. no. of employees for those dept. are greater than 5) and it also further filters only department D1 and D2 using IN(list...) query.

So, option 2 is correct answer.

Reference : SQL HAVING Clause Example

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UGC NET CS December 2019 - Question 71	UGC NET CS December 2019 - Question 73

UGC NET Computer Science December 2019 | Question 74

Question 74
A counting semaphore is initialized to 8. 3 wait() operations and 4 signal() operations are applied. Find the current value of semaphore variable.

1. 9
2. 4
3. 1
4. 4

Answer : 1. 9

Explanation

In counting semaphore, Wait operations will decrease the value and signal operations will increase the value.
Initially counting semaphore value is 8.
3 Wait operations= - 3
4 Signal operation= + 4
= 8 - 3 + 4
= 5 + 4
= 9

So, option 1 is correct answer

Counting semaphore can take non-negative integer values.
Two standard operations, wait and signal are defined on the semaphore. Entry to the critical section is controlled by the wait operation and exit from a critical region is taken care by signal operation. The wait, signal operations are also called P and V operations. The manipulation of semaphore (S) takes place as following:

The wait command P(S) decrements the semaphore value by 1. If the resulting value becomes negative then P command is delayed until the condition is satisfied.
The V(S) i.e. signals operation increments the semaphore value by 1

Reference : OS Semaphores

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UGC NET CS December 2019 - Question 73	UGC NET CS December 2019 - Question 75

UGC NET Computer Science December 2019 | Question 78

Question 78
Suppose a system has 12 magnetic tape drives and at time t₀. three processes are allotted tape drives out of their need as given below:

Process Maximum
Needs Current
Needs
P₀ 10 5
P₁ 4 2
P₂ 9 2

At time t₀, the system is in safe state. Which of the following is safe sequence so that deadlock is avoided?

1. ( P₀, P₁, P₂ )
2. ( P₁, P₀, P₂ )
3. ( P₂, P₁, P₀ )
4. ( P₀, P₂, P₁ )

Answer : 2. (P₁, P₀, P₂ )

Explanation

Out of Total 12 magnetic tape drives, 9 magnetic tape drives are allocated. So There are 3 remaining magnetic tape drives.

Process	Maximum Needs	Allocated resources	Remaining Needs
P₀	10	5	5
P₁	4	2	2
P₂	9	2	7

With available 3 magnetic tape drives, process P₁ requirements of 2 magnetic tape drives can be fulfilled. So, after completion of process P₁, it releases total 4 magnetic tape drives.

Now, with available tap drives are 4 + 1 = 5,
Process P₀ requirements of 5 magnetic tape drives can only be fulfilled. So, after completion of process P₀, it releases total 10 magnetic tape drives.

Now, available tap drives are 10,
Process P₂ requirements of 9 magnetic tape drives can be fulfilled.
Process P₂ will completed wihtout deadlock.

The only safe sequence that avoide deadlock is (P1, P0, P2). So, that system is in safe state for given process needs.

So, option 2 is correct answer

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UGC NET CS December 2019 - Question 77	UGC NET CS December 2019 - Question 79

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