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UGC NET Computer Science Previous Year Questions (PYQs)

UGC NET Computer Science 2023 PYQ


UGC NET Computer Science PYQ 2023
Consider a hash table of size seven with starting index zero and a hash function $(6x + 3) \mod 4$. Assuming the hash table is initially empty. Which of the following is the content of the table when the sequence 1, 3, 8, 10, 5 is inserted into the table using closed hashing? Here “_______” denotes an empty location in the table.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Hash function:

$h(x) = (6x + 3) \mod 4$

For 1:

$h(1) = 9 \mod 4 = 1$

So, 1 is placed at index 1.

For 3:

$h(3) = 21 \mod 4 = 1$

Index 1 is occupied, so place 3 at next free index 2.

For 8:

$h(8) = 51 \mod 4 = 3$

So, 8 is placed at index 3.

For 10:

$h(10) = 63 \mod 4 = 3$

Index 3 is occupied, so place 10 at index 4.

For 5:

$h(5) = 33 \mod 4 = 1$

Index 1, 2, 3, 4 are occupied, so place 5 at index 5.

Final table:

_, 1, 3, 8, 10, 5, _

UGC NET Computer Science PYQ 2023
Consider the following finite automata F1 that accepts a language L.


Let F2 be a finite automata which is obtained by reversal of F1. Then which of the following is correct?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

In the given automata, transitions are present in both directions among the states. Therefore, reversing the automata does not change the accepted language.

So,

$L(F1) = L(F2)$

UGC NET Computer Science PYQ 2023
The compiler for high level language that runs on one machine and produces code for other machine is called-





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

A compiler that runs on one machine but generates code for another machine is called a cross compiler.

UGC NET Computer Science PYQ 2023
Which of the following is not a property of a good system for representation of knowledge in a particular domain?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

A good knowledge representation system has the following properties:

Representational adequacy

Inferential adequacy

Inferential efficiency

Acquisitional efficiency

Here, “Presentation adequacy” is not a standard property.

UGC NET Computer Science PYQ 2023
What is x in the following program?
#include <stdio.h>

int main()
{
    typedef (*(*arrfptr[3])())[10];

    arrfptr x;

    return 0;
}





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

The declaration:

typedef (*(*arrfptr[3])())[10];

means arrfptr is an array of 3 pointers to functions.

So,

arrfptr x;

declares x as an array of three function pointers.

UGC NET Computer Science PYQ 2023
The maximum yield length of the following CNF CFG is

S → AB

A → CD

B → e

C → a

D → b





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

In CNF, for a finite grammar, if there are n variables, then maximum yield length can be up to:

$2^{n-1}$

Here, the variables considered are:

A, B, C, D

So,

$n = 4$

Maximum yield length:

$2^{4-1} = 2^3 = 8$

UGC NET Computer Science PYQ 2023
In the standard Ethernet with transmission rate of 10 Mbps, assume that the length of the medium is 2500 m and size of a frame is 512 bytes. The propagation speed of a signal in a cable is normally $2 \times 10^8$ m/s. The transmission delay and propagation delay are





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Transmission delay:

Frame size = 512 bits

Transmission rate = 10 Mbps

Transmission delay:

$\frac{512}{10 \times 10^6} = 51.2\ \mu s$

Propagation delay:

Distance = 2500 m

Speed = $2 \times 10^8$ m/s

Propagation delay:

$\frac{2500}{2 \times 10^8} = 12.5\ \mu s$

UGC NET Computer Science PYQ 2023
Match List I with List II
 LIST I

 LIST II

 A. Critical region

 I. Hoare's monitor

 B. Wait signal

 II. Mutual exclusion

 C. Working set

 III. Principle of locality

 D. Deadlock

 IV. Circular wait

Choose the correct answer from the options given below:






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Critical region is related to mutual exclusion.

Wait signal is related to Hoare's monitor.

Working set is based on principle of locality.

Deadlock is related to circular wait.

So,

A – II, B – I, C – III, D – IV


UGC NET Computer Science PYQ 2023
__________ is intended to show that a system both conforms to its specifications and meets the expectations of the system customer.






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Software validation checks whether the software meets the requirements and expectations of the customer.


UGC NET Computer Science PYQ 2023
Which is not the component of the natural language understanding process?






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Morphological analysis, semantic analysis and pragmatic analysis are standard components of natural language understanding.


Meaning analysis is not a standard separate component because meaning is covered under semantic analysis.


UGC NET Computer Science PYQ 2023
If A = {4n + 2 | n is a natural number} and B = {3n | n is a natural number}. Which of the following is correct for A ∩ B?






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

A contains numbers of the form:


$4n + 2$


So, numbers in A are:


$6, 10, 14, 18, 22, 26, 30, ...$


B contains multiples of 3:


$3, 6, 9, 12, 15, 18, 21, 24, 27, 30, ...$


Common elements are:


$6, 18, 30, 42, ...$


These can be written as:


$12n - 6$


UGC NET Computer Science PYQ 2023
The total cost of retrieving records in sorted order using an unclustered B+ tree is

(P – Average number of records per data page

N – Data pages

F – Ratio of the size of a data entry to the size of a data record)






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

In an unclustered B+ tree, retrieving records in sorted order requires scanning index entries and then fetching records from data pages.


Cost of scanning leaf level entries:


$F \times N$


Number of records:


$P \times N$


So, total cost:


$FN + PN = (F + P)N$


Final Answer: (b) (F + P) * N


UGC NET Computer Science PYQ 2023
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

A virtual memory system uses first-in first-out page replacement policy and allocates a fixed number of frames to a process.

Assertion A: Increasing number of page frames allocated to a process sometimes increases the page fault rate.

Reason R: Some programs do not exhibit locality of reference.

In the light of the above statements, choose the correct answer from the options given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Assertion A is true because FIFO page replacement may show Belady’s anomaly.


In Belady’s anomaly, increasing the number of page frames can sometimes increase the number of page faults.


Reason R is true, but it is not the correct explanation of Assertion A.


UGC NET Computer Science PYQ 2023
At a particular time of computation, the value of a counting semaphore is 7. Then 20 P operations and x V operations were completed on this semaphore. If the final value of semaphore is 5, x will be





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Solution

Initial semaphore value = 7


Each P operation decreases the value by 1.


Each V operation increases the value by 1.


So,


$7 - 20 + x = 5$


$x - 13 = 5$


$x = 18$


UGC NET Computer Science PYQ 2023
A processor chip is used for application in which 30% of execution time is spent on floating point addition. For the new model of the processor, the design team has come up with redesign the floating point adder to make it twice as fast. What will be possible maximum speed up by this redesign?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Using Amdahl’s law:


Fraction improved = $0.30$


Speedup of improved part = $2$


Overall speedup:


$S = \frac{1}{(1 - 0.30) + \frac{0.30}{2}}$


$S = \frac{1}{0.70 + 0.15}$


$S = \frac{1}{0.85}$


$S = 1.176 \approx 1.18$


UGC NET Computer Science PYQ 2023
Which of the following transforms in 2 dimension is used to resize a 2-dimensional object?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Scaling transformation is used to increase or decrease the size of a 2-dimensional object.


UGC NET Computer Science PYQ 2023
A three dimensional array in C++ is declared as int A [a] [b] [c]. Consider that array elements are stored in row major order and indexing begin from 0. Here the address of an item at the location A [r] [s] [t] computed in terms of word length w of an integer is





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

For a 3D array $A[a][b][c]$ stored in row major order:


Address of $A[r][s][t]$ is


Base address + $w[(r \times b \times c) + (s \times c) + t]$


So,


Address = $ A[0][0][0] + w(bcr + c*s + t)$


UGC NET Computer Science PYQ 2023
Which of the following is used to determine the cost performance index?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Cost Performance Index is calculated as:


$CPI = \frac{BCWP}{ACWP}$


That means:


Budgeted cost of work performed ÷ Actual cost of work performed


UGC NET Computer Science PYQ 2023
A TCP server application is programmed to listen on port P on host S. A TCP client is connected to the TCP server over the network. Consider that while TCP connection is active the server is crashed and rebooted. Assume that the client does not use TCP keepalive timer. Which of the following behaviour/s is/are possible?

Statement I: The TCP application server on S can listen on P after reboot.

Statement II: If client sends a packet after the server reboot, it will receive the RST segment.

In the light of the above statements, choose the correct answer from the options given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

After reboot, the TCP server can again start listening on port P.


The old TCP connection state is lost after reboot. So, if the client sends a packet for the old connection, the server does not recognize it and sends an RST segment.


UGC NET Computer Science PYQ 2023
Consider a popular sports news site. At a given moment, 20,000 concurrent users submit a request, a transaction T, once every 2 minutes on average. Each transaction requires the webapp to download a new article that on average has 3k bytes in length. What is the throughput?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Number of transactions per second:


$ \frac{20000}{120} = 166.67 $


Size of each article:


$3k$ bytes $= 3000$ bytes


$3000$ bytes $= 3000 \times 8 = 24000$ bits


Throughput:


$166.67 \times 24000 = 4000000$ bits per second


$= 4$ megabits per second


UGC NET Computer Science PYQ 2023
Consider the following statements:

A. A database design is in BCNF if each member of the set of relation schemas that constitutes the design is in BCNF

B. A BCNF schema can have transitive dependency

C. It is always possible to obtain a 3NF design without sacrificing a lossless join

D. There are multivalued dependencies in 4NF





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

A is correct because a database design is in BCNF when every relation schema in the design is in BCNF.


B is incorrect because BCNF removes dependency problems caused by non-super-key determinants.


C is correct because 3NF decomposition can be made lossless.


D is correct because 4NF deals with multivalued dependencies.


UGC NET Computer Science PYQ 2023
Which is not a basic approach to the problem of conflict resolution in a production system?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

In a production system, conflict resolution can be based on the rule matched, the object matched, or the action of the matched rule.


But assigning preference based on the action that the matched object would perform is not a standard conflict resolution approach.


UGC NET Computer Science PYQ 2023
Consider the following statements:

S1: LRU page replacement algorithm suffers from the Belady's anomaly

S2: Shortest remaining time first scheduling may cause starvations

S3: Stack is shared by all threads in a process





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

S1 is false because LRU does not suffer from Belady’s anomaly.


S2 is true because shortest remaining time first may cause starvation for long processes.


S3 is false because each thread has its own stack.


Final Answer: (b) S1, S3 false and S2 is true


UGC NET Computer Science PYQ 2023
Let $R(A, B, C, D, E)$ be a relational schema with following functional dependencies:

$C \to F,\ E \to A,\ EC \to D,\ A \to B$

Which of the following is a key for R?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Find closure of $EC$:


$EC^+ = {E, C}$


Using $E \to A$,


$EC^+ = {E, C, A}$


Using $A \to B$,


$EC^+ = {E, C, A, B}$


Using $EC \to D$,


$EC^+ = {E, C, A, B, D}$


So, $EC$ determines all attributes.


UGC NET Computer Science PYQ 2023
Match List I with List II
 LIST I

LIST II

 
 A. Physical layer

 I. Transforming the raw bits in the form of frame for transmission

 B. Data Link Layer

 II. Control and monitoring of subnet

 C. Network layer

III. Transmission of raw bits over communication channel

 
 D. Transport layer

 IV. Datagrams transmission data through connection oriented or connectionless using datagram

Choose the correct answer from the options given below:






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

hysical layer deals with transmission of raw bits.


Data Link Layer converts raw bits into frames.


Network layer controls and monitors subnet.


Transport layer supports connection-oriented and connectionless transmission.


So,


A – III, B – I, C – II, D – IV


UGC NET Computer Science PYQ 2023
A B-tree used as an index for a large database table has four levels including the root node. If a new key is inserted in this index, then maximum number of nodes that could be newly created in the process is





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

In worst case, insertion causes splitting at every level.


There are 4 levels, so 4 new nodes may be created due to splitting.


If the root also splits, one extra new root node is created.


Maximum newly created nodes:


$4 + 1 = 5$


UGC NET Computer Science PYQ 2023
Suppose a circular queue of capacity $(n - 1)$ elements is implemented with an array of $n$ elements. Assume that the insertion and deletion operations are carried out using REAR and FRONT as array index variable respectively. Initially, REAR = FRONT = 0. The conditions to detect queue empty and queue full are





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

In a circular queue with capacity $(n - 1)$:

Queue is empty when:

REAR == FRONT

Queue is full when the next position of REAR becomes FRONT:

$(REAR + 1) \mod n == FRONT$

UGC NET Computer Science PYQ 2023
Match List I with List II
 LIST I

LIST II 

 A. Scenario testing
 I. To verify the I/O behavior of text object
 B. Regression testing
 II. User acceptance methodology
 C. Component testing
 III. No new bugs after changes in program
 D. Beta testing

 IV. The documentation of a use case

Choose the correct answer from the options given below:






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Scenario testing is related to documentation of a use case.

Regression testing checks that no new bugs are introduced after changes.

Component testing verifies input and output behavior of a component.

Beta testing is related to user acceptance methodology.

UGC NET Computer Science PYQ 2023
Given below are two statements:

Let $f(n)$ and $g(n)$ be asymptotically positive functions. The following conjectures are given.

Statement I: $f(n) \ge 1$ and $f(n)=O(g(n)) \Rightarrow g(n)=\Omega(f(n))$

Statement II: $f(n)=O(g(n)) \Rightarrow \lg(f(n))=O(\lg(g(n)))$ where $\lg(g(n)) \ge 1$ for all sufficiently large $n$.

In the light of the above statements, choose the most appropriate answer from the options given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

tatement I is correct because $f(n)=O(g(n))$ directly implies $g(n)=\Omega(f(n))$.

Statement II is not always correct, because taking logarithm on both sides of Big-O relation is not valid in all cases unless extra conditions are satisfied.

UGC NET Computer Science PYQ 2023
Consider the rectangle with vertices $(0,0)$, $(0,2)$, $(3,0)$, $(3,2)$. There is scaling of 2 towards x-axis and 3 towards y-axis. The new coordinates of the rectangle are





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Scaling factor along x-axis = $2$

Scaling factor along y-axis = $3$

So,

$(0,0) \to (0,0)$

$(0,2) \to (0,6)$

$(3,0) \to (6,0)$

$(3,2) \to (6,6)$

UGC NET Computer Science PYQ 2023
What is the $(4+4)$ bit binary fixed point equivalent of $-(3.72)_{10}$?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

First convert positive $3.72$ approximately in $(4+4)$ fixed point form.

$3.72 \approx 3.75$

$3 = 0011$

$0.75 = .1100$

So,

$3.75 = 0011.1100$

For negative number, take 2’s complement:

$0011.1100 \to 1100.0100$

UGC NET Computer Science PYQ 2023
Consider following statements:

A. A context free language is generated by LR(0) grammar if and only if it is accepted by a deterministic pushdown automata and has prefix property.

B. If M1 is the single tape TM simulating multitape TM M, then time taken by M1 to simulate n moves is $(n^3)$.

C. Push down automata behaves like a Turing machine when it has one auxiliary memory.

D. $L={a^n b^n c^n : n \ge 1}$ is not context free but context sensitive.

Choose the correct answer from the options given below:





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Solution

A is incorrect because LR(0) is a restricted class and the statement is not generally true.

B is incorrect because a single-tape TM can simulate a multitape TM with quadratic overhead, not cubic.

C is incorrect because a pushdown automata with one stack is not equivalent to a Turing machine.

D is correct because $L={a^n b^n c^n : n \ge 1}$ is not context free, but it is context sensitive.

UGC NET Computer Science PYQ 2023
Match List I with List II
 LIST I

LIST II 

 A. PERT

 I. Used for non repetitive jobs

 B. Optimistic time

 II. Used for repetitive jobs

 C. CPM

 III. The shortest possible time to complete the activity if all goes well

 D. Pessimistic time

 IV. The longest time that an activity takes

Choose the correct answer from the options given below:






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

PERT is used for non repetitive jobs.

Optimistic time means the shortest possible time if everything goes well.

CPM is used for repetitive jobs.

Pessimistic time means the longest possible time an activity may take.

So,

A – I, B – III, C – II, D – IV


UGC NET Computer Science PYQ 2023
Match List I with List II
 LIST I

LIST II 

A. Bezier curves

I. 3 dim objects that have translation rotational symmetry

B. B-Splines

II. Fractal geometry

C. Sweep representations

III. Bias and tension

D. Natural objects

IV. Painting drawing CAD

Choose the correct answer from the options given below:






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Bezier curves are commonly used in painting, drawing and CAD.


B-Splines are related to bias and tension.


Sweep representations are used for 3D objects having translational or rotational symmetry.


Natural objects are represented using fractal geometry.


So,


A – IV, B – III, C – I, D – II


UGC NET Computer Science PYQ 2023
Given below are two statements:

Statement I: If f and g are two functions and f = O(g) but g ≠ o(f), we say that the growth rate of g is smaller than that of f.

Statement II: The class of all decision problems decided by a TM in exponential time, that is O(2^k), k being a constant.

In the light of the above statements, choose the most appropriate answer from the options given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Statement I is incorrect because if f = O(g), then f grows no faster than g. So, g is not smaller than f.

Statement II is also incorrect because exponential time is generally represented as exponential in input size, not O(2^k) where k is a constant.


UGC NET Computer Science PYQ 2023
What is the output of following code?

main()
{
static float a[] = {13.24, 1.5, 4.5, 5.4, 3.5}

float *j, *k;

j = a;

k = a + 4

j = j * 2;

k = k/2;

printf("% f% f", *j, *k);

}





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

In C, pointer multiplication and pointer division are not allowed.


Here,


j = j * 2;


and


k = k / 2;


are invalid operations.


UGC NET Computer Science PYQ 2023
There are M points on one straight line AB and n points on another straight line AC none of them being A. How many triangles can be formed with these points as vertices?





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Solution

To form a triangle, we can choose:


2 points from line AB and 1 point from line AC


or


2 points from line AC and 1 point from line AB


Number of triangles:


$ {m \choose 2}n + {n \choose 2}m $


$ = \frac{m(m-1)}{2}n + \frac{n(n-1)}{2}m $


$ = \frac{mn}{2}[(m-1)+(n-1)] $


$ = \frac{1}{2}mn(m+n-2) $


UGC NET Computer Science PYQ 2023
Consider two hosts P and Q that are connected through a router R. The maximum transfer unit (MTU) value of the link between P and R is 1500 bytes and between R and Q is 820 bytes. A TCP segment of size 1400 bytes is transferred from P to Q through R with IP identification value of 0x1234. Assume that IP header size is 20 bytes. Further the packet is allowed to be fragmented, that is Don't fragment (DF) flag in the IP Header is not set by P. Which of the following statement/s is/are true?

A. Two fragments are created at R and IP datagram size carrying the second fragment is 620 bytes

B. If the second fragment is lost, then R resends the fragment with IP identification value of 0x1234

C. If the second fragment lost, then P requires to resend the entire TCP segment.

D. TCP destination port can be determined by analyzing the second fragment only.

Choose the correct answer from the options given below:





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

TCP segment size = 1400 bytes

IP header size = 20 bytes

MTU between R and Q = 820 bytes

Maximum data per fragment:

$820 - 20 = 800$ bytes

So fragments will be:

First fragment data = $800$ bytes

Second fragment data = $600$ bytes

Second IP datagram size:

$600 + 20 = 620$ bytes

So, A is true.

Router does not resend lost fragments, so B is false.

If a fragment is lost, source P retransmits the whole TCP segment, so C is true.

TCP header is present only in the first fragment, so destination port cannot be determined from the second fragment only. Hence D is false.

UGC NET Computer Science PYQ 2023
Which of the following is not a mutation operator in a genetic algorithm?

A. Random resetting

B. Scramble

C. Inversion

D. Difference

Choose the correct answer from the options given below:





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Random resetting, scramble and inversion are mutation operators in genetic algorithms.

Difference is not a standard mutation operator.

UGC NET Computer Science PYQ 2023
Consider the following statements:

A. If some NP-complete problem P is in P that P = NP

B. TSP is in NP

C. SAT is in NP

D. Hamilton circuit problem is not NP-complete

Choose the correct answer from the options given below:





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Solution

A is true because if any NP-complete problem is solved in polynomial time, then $P = NP$.

B is true because TSP decision problem is in NP.

C is true because SAT is in NP.

D is false because Hamilton circuit problem is NP-complete.

UGC NET Computer Science PYQ 2023
Consider the following statements about heap sort algorithm:

A. The MAX-HEAPIFY procedure which runs in $O(\lg n)$ time, is the key to maintaining the max heap property

B. The BUILD-MAX-HEAP procedure, which runs in $O(\lg n)$ time, produces max-heap from an unordered input array

C. The MAX-HEAP-INSERT, which runs in $O(\lg n)$ time, implements the insertion operation

D. The HEAP-INCREASE-KEY procedure runs in $O(n \lg n)$ time, to set the key of new node of its correct value

Choose the correct answer from the options given below:





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

A is true because MAX-HEAPIFY takes $O(\lg n)$ time.

B is false because BUILD-MAX-HEAP takes $O(n)$ time, not $O(\lg n)$.

C is true because MAX-HEAP-INSERT takes $O(\lg n)$ time.

D is false because HEAP-INCREASE-KEY takes $O(\lg n)$ time, not $O(n \lg n)$.

UGC NET Computer Science PYQ 2023
Consider the following statements about the software product line system:

Statement I: At the interaction level, components provide an operator display interface and an interface with the communication system used.

Statement II: At the I/O management level, components handle operator authentication, report generator and query manager.

In the light of the above statements, choose the most appropriate answer from the options given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Statement I is correct because interaction level provides operator display interface and communication interface.

Statement II is also correct because I/O management level handles authentication, report generation and query management.

UGC NET Computer Science PYQ 2023
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: The AVL trees are more balanced as compared to Red Black trees, but they may cause more rotations during insertion and deletion.

Reason R: A Red Black tree with n nodes has height that is greater than $2\log_2(n+1)$ and the AVL tree with n nodes has height less than $\log_\phi(\sqrt{5}(n+2))-2$ where $\phi$ is golden ratio.

In the light of the above statements, choose the correct answer from the options given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Assertion A is true because AVL trees are more strictly balanced than Red Black trees.

Reason R is false because the height of a Red Black tree is at most $2\log_2(n+1)$, not greater than it.

UGC NET Computer Science PYQ 2023
256 Mb DRAM is organized as a 32M × 8 memory externally and as a 16K × 16K square array internally. Each row must be refreshed at least once every 50 millisecond to forestall loss of data; refreshing one row takes 100 nanoseconds. What fraction of the total memory bandwidth is lost to refresh cycles?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Number of rows = $16K = 16384$

Refresh time for one row = $100$ ns

Total refresh time:

$16384 \times 100 = 1638400$ ns

$= 1.6384$ ms

Fraction of time lost:

$\frac{1.6384}{50} \times 100 = 3.2768% \approx 3.3%$

UGC NET Computer Science PYQ 2023
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: Validity checks real need of system users.

Reason R: Completeness checks system user defined requirements.

In the light of the above statements, choose the correct answer from the options given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Assertion A is true because validity checks whether requirements match the real needs of users.

Reason R is also true because completeness checks whether all user-defined requirements are included.

But Reason R does not explain Assertion A.

UGC NET Computer Science PYQ 2023
Given the basic E R diagram and relational model, which of the following is incorrect?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

In the E R model, an attribute can be multivalued or composite.

But in the relational model, each cell of a table should contain a single atomic value or NULL.

UGC NET Computer Science PYQ 2023
Match List I with List II
 LIST I

LIST II 

 A. Expert system

 I. Decision tree

 B. Fuzzy system

 II. Scramble

 C. Operator in genetic algorithm

 III. Inference engine

 D. Supervised technique

 IV. Mycin

Choose the correct answer from the options given below:






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Expert system is related to Mycin.

Fuzzy system uses an inference engine.

Scramble is an operator in genetic algorithm.

Decision tree is a supervised learning technique.

So,

A – IV, B – III, C – II, D – I

UGC NET Computer Science PYQ 2023
In a multi user operating system, 20 requests are made to use a particular resource per hour, on an average. The probability that no request is made in 45 minutes is





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Average requests per hour = $20$

Time = $45$ minutes $= \frac{3}{4}$ hour

Mean number of requests in $45$ minutes:

$\lambda = 20 \times \frac{3}{4} = 15$

Using Poisson distribution:

$P(X=0)=e^{-\lambda}\frac{\lambda^0}{0!}$

$P(X=0)=e^{-15}$

UGC NET Computer Science PYQ 2023
Given below are two statements:

Statement I: Subsystem models show logical grouping of objects into coherent subsystem

Statement II: State machine models show how objects change their states in response to events.

In the light of the above statements, choose the most appropriate answer from the options given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Statement I is correct because subsystem models represent logical grouping of objects into subsystems.

Statement II is correct because state machine models show state changes of objects due to events.

UGC NET Computer Science PYQ 2023
How many integral solutions are there to $x+y+z+w=29$, where $x \ge 1$, $y \ge 2$, $z \ge 3$ and $w \ge 0$?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Let

$x'=x-1,\ y'=y-2,\ z'=z-3,\ w'=w$

Then,

$x'+y'+z'+w'=29-1-2-3=23$

Number of non-negative integral solutions:

${23+4-1 \choose 4-1}={26 \choose 3}$

$= \frac{26 \times 25 \times 24}{3 \times 2 \times 1}$

$=2600$

UGC NET Computer Science PYQ 2023
Let $\oplus$ denote XOR operation. Let 1 and 0 denote the binary constants and F is the Boolean expression over two variables P and Q

$F(P,Q)=((1\oplus P)\oplus(P\oplus Q))+((P\oplus Q)\oplus(Q\oplus0))$

Which of the following is equivalent expression to F?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

$((1\oplus P)\oplus(P\oplus Q))$

$=1\oplus P\oplus P\oplus Q$

$=1\oplus Q$

$=\overline{Q}$

Second part:

$((P\oplus Q)\oplus(Q\oplus0))$

$=P\oplus Q\oplus Q\oplus0$

$=P$

So,

$F=\overline{Q}+P$

$F=P+\overline{Q}$

This expression is not matching exactly with the given options. So, the correct simplified expression should be:

$P+\overline{Q}$

UGC NET Computer Science PYQ 2023
Let $(Z,+)$ denote the group of all integers under addition. Then the number of all automorphisms of $(Z,+)$ is





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

An automorphism of $(Z,+)$ is completely determined by the image of $1$.

The image of $1$ must be a generator of $Z$.

The generators of $Z$ are:

$1$ and $-1$

So, there are only two automorphisms:

$f(n)=n$

$f(n)=-n$

UGC NET Computer Science PYQ 2023
Which one of the following is NOT a part of ACID properties of a database transaction?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

ACID properties are:

Atomicity

Consistency

Isolation

Durability

Deadlock-freedom is not a part of ACID properties.

UGC NET Computer Science PYQ 2023
Consider the following statements:

A. The set of Turing machine codes for TM's that accept all inputs that are palindromes possible along with some other inputs is decidable

B. The language of codes for TM's M that when started with blank tape, eventually write a 1 somewhere on the tape is undecidable

C. The language accepted by a TM M is L(M) is always recursive

D. Post's correspondence problem is undecidable

Choose the correct answer from the options given below:





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

A is false because checking whether a TM accepts all palindromes is an undecidable property.

B is true because checking whether a TM writes 1 on a blank tape is undecidable.

C is false because the language accepted by a TM is recursively enumerable, but not always recursive.

D is true because Post's correspondence problem is undecidable.

UGC NET Computer Science PYQ 2023
Match List I with List II
 LIST I

LIST II 

 A. CDMA

 I. It provides mobile internet connection with faster data transfer rates

 B. GSM

 II. It allows user to connect to a network or to other devices over wireless channel

 C. UMTS

 III. Accessing mechanism for multiple transmitters over a single channel
 D. WiFi

 IV. It is a cellular technology that employs hybrid of FDMA and TDMA

Choose the correct answer from the options given below:






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

CDMA is an accessing mechanism for multiple transmitters over a single channel.

GSM uses a hybrid of FDMA and TDMA.

UMTS provides faster mobile internet connection.

WiFi allows users to connect to a network over a wireless channel.

So,

A – III, B – IV, C – I, D – II

UGC NET Computer Science PYQ 2023
Consider universe positive integer $X = {1 \le n \le 8}$, proposition P = "n is an even integers", Q = "$(3 \le n \le 7) \land (n \ne 6)$". Then truth set of $P \leftrightarrow Q$ is






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Universe:

$X = {1,2,3,4,5,6,7,8}$

P is true for even integers:

$P = {2,4,6,8}$

Q is true for:

$Q = {3,4,5,7}$

$P \leftrightarrow Q$ is true when both P and Q have same truth value.

Both true:

$P \cap Q = {4}$

Both false:

Elements not in $P \cup Q = {1}$

Therefore,

Truth set = ${1,4}$

UGC NET Computer Science PYQ 2023
An observational technique that can be used to understand operational process and help to derive requirement for software to support operational process is known as





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Ethnography is an observational technique used to understand real work practices and operational processes.

UGC NET Computer Science PYQ 2023
Consider the following program fragment that deals with a table T with 17 rows and 1024 columns, computing an average for each column and printing it to screen, where i is row index and j is column index:

for j = [0.....1023] {

temp = 0;

for i = [0.....16]:

temp = temp + T[i][j];

print(temp/17.0);

}

T[i][j] and temp are 32 bit floating point values and memory is word addressable. The temporary variable temp is kept in a processor register so access to temp does not involve a memory reference. The main memory is paged and holds 16 pages of size 1024 words, the page replacement policy is least recently used. If T is stored in the virtual address space in row major format.

What is the main memory hit ratio?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

In row major format, each row has 1024 elements.

Page size = 1024 words

So, each row occupies exactly 1 page.

There are 17 rows, so there are 17 pages.

For each column, access pattern is:

$T[0][j], T[1][j], T[2][j], ..., T[16][j]$

This means 17 different pages are accessed repeatedly.

But main memory can hold only 16 pages.

Using LRU, every access causes a page fault.

So, hit ratio = 0

UGC NET Computer Science PYQ 2023
Consider again that T is stored in column major format, what is the main memory hit ratio?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

In column major format, elements of each column are stored continuously.

Each column has 17 elements.

Total elements:

$17 \times 1024 = 17408$

Page size = 1024 words

Total pages:

$\frac{17408}{1024}=17$

Since access is column-wise, memory access is almost sequential.

Only 1 page fault occurs per page.

Total page faults = 17

Total memory references = 17408

Hits:

$17408 - 17 = 17391$

Hit ratio:

$\frac{17391}{17408} \times 100 \approx 99.9%$

UGC NET Computer Science PYQ 2023
Consider the following program fragment that deals with a table T with 17 rows and 1024 columns, computing an average for each column and printing it to screen, where i is row index and j is column index:

for j = [0.....1023] {

temp = 0;

for i = [0.....16]:

temp = temp + T[i][j];

print(temp/17.0);

}

T[i][j] and temp are 32 bit floating point values and memory is word addressable. The temporary variable temp is kept in a processor register so access to temp does not involve a memory reference. The main memory is paged and holds 16 pages of size 1024 words, the page replacement policy is least recently used.

Consider that T is stored in column major format, how many page faults will be encountered?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Total elements in table T:

$17 \times 1024 = 17408$

Page size:

$1024$ words

Number of pages required:

$\frac{17408}{1024}=17$

In column major format, the program accesses elements column by column, so memory access is sequential.

Each page will cause one page fault.

Therefore,

Total page faults = $17$

UGC NET Computer Science PYQ 2023
Consider the following program fragment that deals with a table T with 17 rows and 1024 columns, computing an average for each column and printing it to screen, where i is row index and j is column index:

for j = [0.....1023] {

temp = 0;

for i = [0....16]:

temp = temp + T[i][j];

print(temp/17.0);

}

T[i][j] and temp are 32 bit floating point values and memory is word addressable. The temporary variable temp is kept in a processor register so access to temp does not involve a memory reference. The main memory is paged and holds 16 pages of size 1024 words, the page replacement policy is "least recently used", if T is stored in the virtual address space in row major format.

How many page faults will be encountered?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

T has 17 rows and 1024 columns.

Page size = 1024 words

Since memory is word addressable and each element is 1 word, each row contains:

$1024$ words

So, in row major format, each row occupies exactly one page.

Total pages for T:

$17$ pages

Main memory can hold only 16 pages.

The program accesses elements column-wise:

$T[0][j], T[1][j], T[2][j], \ldots, T[16][j]$

So, for each column, it accesses 17 different pages.

Since memory can hold only 16 pages and LRU is used, every access causes a page fault.

Total memory accesses:

$17 \times 1024 = 17408$

Therefore, total page faults:

$17408$

UGC NET Computer Science PYQ 2023
Consider the following program fragment that deals with a table T with 17 rows and 1024 columns, computing an average for each column and printing it to screen, where i is row index and j is column index:

for j = [0.....1023] {

temp = 0;

for i = [0.....16]:

temp = temp + T[i][j];

print(temp/17.0);

}

T[i][j] and temp are 32 bit floating point values and memory is word addressable. The temporary variable temp is kept in a processor register so access to temp does not involve a memory reference. The main memory is paged and holds 16 pages of size 1024 words, the page replacement policy is "least recently used", if T is stored in the virtual address space in row major format.

What is fault ratio of row major to column major arrangements?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

For row major arrangement:

Each row has 1024 elements.

Page size = 1024 words

So, each row occupies 1 page.

Total rows = 17, so total pages = 17.

Main memory can hold only 16 pages.

The program accesses column-wise:

$T[0][j], T[1][j], T[2][j], ..., T[16][j]$

So, every access causes a page fault.

Row major page faults:

$17 \times 1024 = 17408$

For column major arrangement:

Elements of each column are stored continuously.

Total elements:

$17 \times 1024 = 17408$

Page size = 1024 words

Column major page faults:

$\frac{17408}{1024} = 17$

Fault ratio:

$17408 : 17 = 1024 : 1$

UGC NET Computer Science PYQ 2023
IP datagram has arrived with following partial information in the header in hexadecimal:

45000054000300002006.....

What is the header size?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

First byte is 45.

Here, 4 represents IPv4 and 5 represents IHL.

Header size = 5 × 4 bytes = 20 bytes

UGC NET Computer Science PYQ 2023
IP datagram has arrived with following partial information in the header in hexadecimal:

45000054000300002006.....

What is the efficiency of this datagram?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Total length field = 0054 hexadecimal

0054 hex = 84 bytes

Header size = 20 bytes

Data size = 84 - 20 = 64 bytes

Efficiency = Data size / Total size × 100

Efficiency = 64 / 84 × 100 = 76.19%

UGC NET Computer Science PYQ 2023
IP datagram has arrived with following partial information in the header in hexadecimal:

45000054000300002006.....

What is the protocol of the payload being carried by the packet?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

In IPv4 header, protocol field is after TTL.

Given header part:

45 00 00 54 00 03 00 00 20 06

Here, protocol field = 06

Protocol number 06 represents TCP.

UGC NET Computer Science PYQ 2023
IP datagram has arrived with following partial information in the header in hexadecimal:

45000054000300002006.....

What is the size of datagram?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Total length field = 0054 hexadecimal

0054 hex = 84 decimal

So, size of datagram = 84 bytes

UGC NET Computer Science PYQ 2023
IP datagram has arrived with following partial information in the header in hexadecimal:

45000054000300002006.....

How many more routers can the packet travel to?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

TTL field is 20 hexadecimal.

20 hex = 32 decimal

TTL shows how many more routers or hops the packet can travel.

UGC NET Computer Science PYQ 2023
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: Dendral is an expert system

Reason R: The rationality of an agent is not related to its reaction to the environment.

In the light of the above statements, choose the correct answer from the options
given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Dendral is an expert system. It was a groundbreaking AI project developed in the 1960s and 1970s aimed at automatically deducing the structure of organic molecules based on their mass spectrometry data. So, assertion A is correct. 

The second statement, however, is incorrect. The rationality of an agent in AI is very much related to its reaction to its environment. Rational agents should be able to make decisions based on their perceptions of the environment in order to achieve the best possible outcome or, in the case of uncertainty, the best expected outcome. Therefore, reason R is false

UGC NET Computer Science PYQ 2023
Match List I with List II
 LIST I LIST II 
 A Δ B (A - B) ∪ (A - C)
 A - (B ∪ C) (A - B) ∩ (A - C)
 A - (B ∩ C) (A - B) ∪ (B - A)
 A ∩ (B - C) (A ∩ B) - (A ∩ C)
Choose the correct answer from the options given below: 





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

• A Δ B:
○ This represents the symmetric difference between sets A and B. It includes all those elements which are in A and B but not in their intersection. Mathematically, it can be represented as (A - B) ∪ (B - A). So, A matches with III.

• A - (B ∪ C):
○ This represents all elements in A not in (B or C). Another way to represent it would be (A - B) ∩ (A - C) because it is the intersection of elements that are only in A and not in B or C. So, B matches with II.

• A - (B ∩ C):
○ This represents all elements in A that are not common to both B and C, or equivalently, the elements just in A and not in the intersection of B and C. So, C matches with I.

• A ∩ (B - C):
○ This represents the intersection of A and the elements in B not in C. It is equivalent to (A ∩ B) - (A ∩ C) because you're taking all elements in both A and B, then removing any elements that are also in C. So, D matches with IV.

Therefore, the correct option is A - III, B - II, C - I, D - IV. So, the correct option is 1).

UGC NET Computer Science PYQ 2023
Which of the following is not a solution representation in a genetic algorithm?
1.Binary valued
2.Real valued
3.Permutation
4.Combinations





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

In a genetic algorithm, solution representation refers to how the potential solutions, or individuals in the population, are encoded. The given options can be categorized as follows:

• Binary valued: Represents solutions using binary encoding, where each gene is typically represented as either 0 or 1.

• Real valued: Represents solutions using real numbers, allowing for a more continuous representation.

• Permutation: Represents solutions as permutations of elements, where the order of elements matters.

• Combinations: This is not a standard representation in genetic algorithms. While permutations represent ordered arrangements, combinations represent unordered selections of elements. Genetic algorithms typically use representations that capture the structure and relationships among elements, and combinations may not be suitable for many optimization problems.


UGC NET Computer Science PYQ 2023
Match List I with List II

 LIST I

 LIST II

 A. Parallel FFT

 I. Θ(n²)
 B. Iterative FFTII. Θ(n) 
 C. Evaluation of polynomial at n points by Horner method III. Θ(lg n)
 D. Product of two polynomials that are represented in point value form IV. Θ(n lg n)
Choose the correct answer from the options given below:





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

A – Parallel Fast Fourier Transform (FFT):

The FFT can be executed in parallel, which reduces the time complexity from O(n log n) to O(log n) under ideal conditions, as the operations required to calculate the FFT can be effectively divided among multiple processors. Thus, it corresponds to III. Θ(lg n).


B – Iterative Fast Fourier Transform (FFT):

The FFT, even when implemented iteratively, has a time complexity of O(n log n) because we divide the problem into smaller chunks recursively, and for each level of division, we do a constant amount of work. Hence it matches with IV. Θ(n lg n).


C – Evaluation of polynomial at n points by Horner method:

If evaluated using the Horner method, a polynomial can be evaluated in O(n) operations. However, if we are evaluating the polynomial at n points, and the polynomial itself has degree n, the total complexity becomes O(n²). Therefore, it corresponds to I. Θ(n²).


D – Product of two polynomials that are represented in point value form:

If the polynomials are represented in point-value form, their product can be computed pretty efficiently in O(n) time complexity. This is due to the fact that to compute the product polynomial at a point, you simply multiply the evaluations of the input polynomials at that point.


Therefore, D corresponds to II. Θ(n).


UGC NET Computer Science PYQ 2023
The following table shows the time between failures for a software:
 Error number: 12 3 4 5 
 Time since last failure (Hours): 6 48 5 6 
The reliability of the system for one hour operation assuming an exponential model is-





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Therefore, the correct option is: Option 3: $e^{-\frac{5}{29}}$

The reliability of a system in the context of reliability engineering is often modeled using the exponential distribution. The exponential reliability function is given by:

$R(t) = e^{-\lambda t}$

where:

• $R(t)$ is the reliability at time $t$,

• $\lambda$ is the failure rate (reciprocal of the mean time between failures).

• In this case, you are given the time between failures for the software:
○ Time between failures = $[6, 4, 8, 5, 6]$

• To find the failure rate $\lambda$, you can use the formula:
○ $\lambda = \frac{1}{\text{Mean time between failures}}$

• Mean time between failures (MTBF) is calculated as the average of the time between failures:
○ $\text{MTBF} = \frac{6+4+8+5+6}{5} = \frac{29}{5}$

• Now, the failure rate $(\lambda)$ is:
○ $\lambda = \frac{1}{\text{MTBF}} = \frac{5}{29}$

• Substitute this into the reliability function:
○ $R(t) = e^{-\frac{5}{29}t}$

• For one hour of operation $(t = 1)$, the reliability becomes:
○ $R(1) = e^{-\frac{5}{29}\times 1} = e^{-\frac{5}{29}}$

So, the correct answer is: $e^{-\frac{5}{29}}$

UGC NET Computer Science PYQ 2023
Given below are two statements:

Which of the following concurrency control protocol ensures both conflict serializability and freedom from deadlock?

Statement I: Two phase locking

Statement II: Timestamp ordering

In the light of the above statements, choose the most appropriate answer from the options given below:





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Two phase locking ensures conflict serializability, but it may cause deadlock. So, it does not ensure freedom from deadlock.

Timestamp ordering ensures conflict serializability and it is deadlock-free because transactions do not wait for locks.

So, Statement I is incorrect and Statement II is correct.

UGC NET Computer Science PYQ 2023
The clipping process in computer graphics is used for





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Clipping in computer graphics is used to remove the portion of objects, lines, or images that lie outside the viewing window.

So, the correct answer is Removing objects and lines.

UGC NET Computer Science PYQ 2023
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: I/O protection is ensured by a hardware trap

Reason R: I/O interrupt caused by the condition like I/O completion and device malfunction occurring within the I/O devices

In the light of the above statements, choose the correct answer from the options given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Assertion A is true because I/O protection is ensured using privileged instructions and hardware trap.

Reason R is also true because I/O interrupts may occur due to I/O completion or device malfunction.

But Reason R does not explain Assertion A.

UGC NET Computer Science PYQ 2023
Let R = {x : x ∈ N, x is multiple of 3 and x ≤ 100} and S = {x : x ∈ N, x is multiple of 5 and x < 100}. What is the number of elements in (R ∩ S) × (S ∩ R)?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Solution: $R=\{x:x\in N,\ x\text{ is multiple of }3,\ x\le 100\}$ $S=\{x:x\in N,\ x\text{ is multiple of }5,\ x<100\}$ $R\cap S$ contains numbers which are multiples of both $3$ and $5$. So, $R\cap S$ contains multiples of $15$. Multiples of $15$ less than $100$ are: $15,30,45,60,75,90$ So, $|R\cap S|=6$ Also, $S\cap R=R\cap S$ Therefore, $|(R\cap S)\times(S\cap R)|=6\times6=36$ So, the correct answer is $36$.

UGC NET Computer Science PYQ 2023
Given below are two statements:

Statement I: Fuzzifier is a part of a fuzzy system

Statement II: Inference engine is a part of fuzzy system

In the light of the above statements, choose the most appropriate answer from the options given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

A fuzzy system generally includes fuzzifier, knowledge base, inference engine, and defuzzifier.

Statement I: Fuzzifier is a part of a fuzzy system. Correct.

Statement II: Inference engine is a part of fuzzy system. Correct.

UGC NET Computer Science PYQ 2023
What will be the output of the following code?
include <stdio.h>

int main() {

int a, b, c;

a = 0x10; b = 010;

c = a + b;

printf("%d", c);

return 0;

}





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

0x10 is a hexadecimal number.

0x10 = 16

010 is an octal number.

010 = 8

So,

c = 16 + 8 = 24

UGC NET Computer Science PYQ 2023
What is the output of following code?

main()

struct s1

{
char *z;

int i;

struct s1 *p;

}

static struct s1 a[] = {

{"Nagpur", 1, a + 1}

{"Raipur", 2, a + 2}

{"Kanpur", 3, a}

};

struct s1 *ptr = a;

printf("%s %s %s\n", a[0].z, ptr -> z, a[2].p -> z);

}





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

a[0].z = Nagpur

ptr = a, so ptr -> z = a[0].z = Nagpur

a[2].p = a, so a[2].p -> z = a[0].z = Nagpur

Final Answer: (b) Nagpur Nagpur Nagpur

UGC NET Computer Science PYQ 2023
Match List I with List II
 List I List II
 A. The running time of straight forward recursive method to compute nth Fibonacci number Fn I. O(n²)
 B. The running time to compute Fn using memoization II. O(lg n)

 C. The running time to compute Fibonacci number Fn using only integer addition and multiplication III. O(n)
 D. The running time to determine an optimal bitonic tour IV. θ(φⁿ)
Choose the correct answer from the options given below:





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

A. Straight forward recursive Fibonacci method takes exponential time.

So, A matches with IV.

B. Fibonacci using memoization takes linear time.

So, B matches with III.

C. Fibonacci number using integer addition and multiplication can be computed in logarithmic time.

So, C matches with II.

D. Optimal bitonic tour takes O(n²) time.

So, D matches with I.

Final Answer: (b) A – IV, B – III, C – II, D – I

UGC NET Computer Science PYQ 2023
Consider a disk system with cylinders. The request to access the cylinders occurs in the following sequence:

4, 34, 10, 7, 19, 73, 2, 15, 6, 20

Assuming that the head is currently at cylinder 50, what is the time taken to satisfy all requests if it takes 1 ms to move from one cylinder to adjacent one and shortest seek time first policy is used?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Using SSTF, the head will move to the nearest request each time.

Movement order:

50 → 34 → 20 → 19 → 15 → 10 → 7 → 6 → 4 → 2 → 73

Total movement:

16 + 14 + 1 + 4 + 5 + 3 + 1 + 2 + 2 + 71 = 119

Since 1 cylinder movement takes 1 ms,

Total time = 119 ms

UGC NET Computer Science PYQ 2023
Find the sum of all four digit numbers formed using the digits 1, 2, 4 and 6.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Digits are 1, 2, 4 and 6.

Sum of digits:

1 + 2 + 4 + 6 = 13

Total four digit numbers formed using all four digits:

4! = 24

Each digit appears 6 times at each place.

So, required sum:

6 × 13 × 1111 = 86658


UGC NET Computer Science PYQ 2023
How will you free the memory allocated by the following program?
#include <stdio.h>

#define MAXROW 3
#define MAXCOL 4

int main()
{
    int **p, i, j;

    p = (int **)malloc(MAXROW * sizeof(int*));

    return 0;
}






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Memory allocated using malloc() is released using free().


Here, memory is allocated to pointer p, so it should be freed as: free(p);


UGC NET Computer Science PYQ 2023
Sutherland Hodgeman method is used on





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Sutherland Hodgeman algorithm is used for polygon clipping, mainly for convex polygons.


UGC NET Computer Science PYQ 2023
Consider the following statements

A. C-Fuzzy means clustering is a supervised method of learning

B. PCA is used for dimension reduction

C. Apriori is not a supervised technique

D. When a machine learning model becomes so specially tuned to its exact input data that it fails to generalize to other similar data it is called underfitting

Choose the correct answer from the options given below:





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

A is false because fuzzy C-means clustering is an unsupervised learning method.


B is true because PCA is used for dimensionality reduction.


C is true because Apriori is an unsupervised association rule mining technique.

D is false because this condition is called overfitting, not underfitting.


UGC NET Computer Science PYQ 2023
Let N denote the set of all natural numbers and R be the relation on N X N defined by (a, b) R(c, d), if ad(b + c) = bc(a + d). Then R is





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

$ad(b+c)=bc(a+d)$


Dividing both sides by $abcd$,


$\frac{b+c}{bc}=\frac{a+d}{ad}$


$\frac{1}{b}+\frac{1}{c}=\frac{1}{a}+\frac{1}{d}$


Rearranging,


$\frac{1}{a}-\frac{1}{b}=\frac{1}{c}-\frac{1}{d}$


So, relation R is based on equality of the same expression.


Therefore, R is reflexive, symmetric and transitive.


UGC NET Computer Science PYQ 2023
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: A process involves a library function to create a thread.

Reason R: The threads make system calls to convey their resource and I/O requirement to the Kernel.

In the light of the above statements, choose the correct answer from the options given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Assertion A is true because threads are generally created using library functions such as pthread_create().


Reason R is also true because threads can make system calls for resource and I/O requirements.


But Reason R does not correctly explain Assertion A.


UGC NET Computer Science PYQ 2023
Let R (A, B, C, D) be a relational schema with following functional dependencies:

$A \to B,\ B \to C$

$C \to D$ and $D \to B$

The decomposition of R into

$(A, B)\ (B, C)\ (B, D)$





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

From the given FDs:

$B \to C$ and $C \to D \Rightarrow B \to D$

So, in relation $(B, D)$, $B$ is a key.

Also, projected dependencies preserve:

$A \to B,\ B \to C,\ D \to B,\ B \to D$

And from

$C \to B$ (via $C \to D$ and $D \to B$), and $B \to D$

we get

$C \to D$

So, decomposition is dependency preserving.

It is also lossless.

UGC NET Computer Science PYQ 2023
Consider the following table of arrival time and burst time for three processes P0, P1, P2:

Process arrival time Burst time

 Processarrival time Burst time 
 P00 ms  7 
P1 1 ms 3 
P2 2ms 7 
The pre-emptive shortest job first scheduling algorithm is used. Scheduling is carried out only at arrival or completion of a process. What is the average waiting time for the three processes?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Scheduling order:

$0$ to $1$: $P0$

At $t=1$, $P1$ arrives, so it preempts $P0$

$1$ to $4$: $P1$ completes

Now remaining:

$P0 = 6,\ P2 = 7$

So,

$4$ to $10$: $P0$ completes

$10$ to $17$: $P2$ completes

Waiting times:

For $P0$:

$10 - 0 - 7 = 3$

For $P1$:

$4 - 1 - 3 = 0$

For $P2$:

$17 - 2 - 7 = 8$

Average waiting time:

$\frac{3+0+8}{3} = \frac{11}{3} = 3.67\ \text{ms}$

UGC NET Computer Science PYQ 2023
Which of the following scenario may lead to an irrecoverable error in a database system?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

An irrecoverable state occurs when a transaction reads a value written by an uncommitted transaction.

This is called a dirty read.

If the writer transaction aborts later, recovery becomes difficult.

UGC NET Computer Science PYQ 2023
Given below are two statements:

Which of the following statement/s is/are correct with respect to virtual memory

Statement I: Address translation is performed for every logical address used during the execution of a program

Statement II: A program can execute only when all of its components are loaded in the memory

In the light of the above statements, choose the most appropriate answer from the options given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Statement I is correct because every logical address is translated into a physical address during execution.

Statement II is incorrect because in virtual memory, all parts of a program need not be loaded into memory at the same time.

UGC NET Computer Science PYQ 2023
Which phase of compiler checks the grammar of programming?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Grammar of a programming language is checked during syntax analysis.

It is also called parsing.

UGC NET Computer Science PYQ 2023
Let $G = \frac{R}{{0}}$ and $H = {-1, 1}$ be groups under the multiplication. Then, the map $\phi : G \to H$ defined by $\phi(x) = \frac{x}{|x|}$ is





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

$\phi(x) = \frac{x}{|x|}$ gives the sign of $x$.

If $x > 0$, then $\phi(x) = 1$

If $x < 0$, then $\phi(x) = -1$

Also,

$\phi(xy) = \phi(x)\phi(y)$

So, it is a homomorphism.

It is onto because both $1$ and $-1$ are obtained.

It is not one-one because many positive numbers map to $1$, and many negative numbers map to $-1$.

UGC NET Computer Science PYQ 2023
Which of the following parser is most powerful parser?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Canonical LR parser is more powerful than SLR, LALR and operator precedence parser.

UGC NET Computer Science PYQ 2023
Which of the following statement is correct?





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

Ackermann's function is not primitive recursive.

$L = {a^n b^k c^{n+k}}$ is not regular.

$L = {a^n b^j : n = j^2}$ is not context free because it has a square relation between powers.

For context sensitive language, there exists an LBA such that $L = L(M)$, not $L \ne L(M)$.

UGC NET Computer Science PYQ 2023
Match List I with List II
 LIST I

 LIST II

 A. RAID level 2

 I. Bit interleaved parity

 B. RAID level 4

 II. Block interleaved distributed parity

 C. RAID level 5

 III. Error correcting parity

 D. RAID level 3

 IV. Block interleaved parity

Choose the correct answer from the options given below:






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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

RAID level 2 uses error correcting parity.

RAID level 4 uses block interleaved parity.

RAID level 5 uses block interleaved distributed parity.

RAID level 3 uses bit interleaved parity.

So,

A – III, B – IV, C – II, D – I

UGC NET Computer Science PYQ 2023
Consider the following statements.

A. The identity is unique in any monoid.

B. A monoid is a group if there exists inverse of each element of monoid.

C. Semi group has closure, associative and identity properties.

D. Quasi group has closure property.

Choose the correct answer from the options given below:





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

A is correct because identity element is always unique in a monoid.

B is correct because a monoid becomes a group if every element has an inverse.

C is incorrect because a semigroup has closure and associative property, but identity is not necessary.

D is correct because a quasigroup has closure property.

UGC NET Computer Science PYQ 2023
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: It is possible to create doubly linked list using only one pointer with every node.

Reason R: By storing the XOR of the addresses of the previous and next nodes.

In the light of the above statements, choose the most appropriate answer from the options given below.





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

A doubly linked list can be implemented using only one pointer field by storing XOR of previous and next node addresses.

This is called XOR linked list.

So, Assertion A is true and Reason R correctly explains A.

UGC NET Computer Science PYQ 2023
Consider the following statements:

A. Dynamic metrics are collected by measurements made of a program in execution

B. Static metrics are collected by measurements made of representations of the system

C. The assessment of software quality is an objective process

D. An important part of quality assurance in the selection of standards that should apply to the software development process.

Choose the correct answer from the options given below:





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

A is correct because dynamic metrics are measured during program execution.

B is correct because static metrics are measured from system representations like code, design, or documents.

C is incorrect because software quality assessment is not fully objective. It also depends on quality factors and requirements.

D is correct because choosing suitable standards is an important part of quality assurance.

UGC NET Computer Science PYQ 2023
Consider the following language: $L = {w \in {a,b,c}^* : na(w) + nb(w) = nc(w)}$ L is





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UGC NET Computer Science UGC NET PYQ UGC NET Computer Science UGC NET Computer Science June 2023 (Paper II) PYQ

Solution

The language contains strings where the number of $c$ symbols is equal to the total number of $a$ and $b$ symbols.

This counting condition can be handled by a context-free grammar, so it is context free.

But it is not linear because arbitrary balanced counting with mixed order needs more than linear grammar power.


UGC NET Computer Science


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