Qus : 6
UGC NET Computer Science PYQ 2020
4
Consider the following properties: A. Reflexive B. Antisymmetric C. Symmetric Let $A=\{a,b,c,d,e,f,g\}$ and $R=\{(a,a),(b,b),(c,d),(c,g),(d,g),(e,e),(f,f),(g,g)\}$ be a relation on $A$. Which of the following property/properties is/are satisfied by the relation $R$?
1
Only A 2
Only c 3
Both A and B 4
B and not A Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution For reflexive relation, every element must have pair $(x,x)$. But $(c,c)$ and $(d,d)$ are missing. So, relation is not reflexive. For antisymmetric relation, if $(x,y)$ and $(y,x)$ both exist, then $x=y$. Here, no reverse pair exists for $(c,d),(c,g),(d,g)$. So, relation is antisymmetric. For symmetric relation, if $(x,y)$ exists, then $(y,x)$ must also exist. But $(c,d)$ exists and $(d,c)$ does not exist. So, relation is not symmetric. Therefore, relation satisfies B and not A.
Qus : 7
UGC NET Computer Science PYQ 2020
2
Consider the following argument with premise $\forall x(P(x)\vee Q(x))$ and conclusion $(\forall xP(x))\wedge(\forall xQ(x))$
(A) $\forall x(P(x)\vee Q(x))$ Premise (B) $P(c)\vee Q(c)$ Universal instantiation from (A) (C) $P(c)$ Simplification from (B) (D) $\forall xP(x)$ Universal generalization of (C) (E) $Q(c)$ Simplification from (B) (F) $\forall xQ(x)$ Universal generalization of (E) (G) $(\forall xP(x))\wedge(\forall xQ(x))$ Conjunction of (D) and (F)
1
This is a valid argument. 2
Steps (C) and (E) are not correct inferences. 3
Steps (D) and (F) are not correct inferences. 4
Step (G) is not a correct inference. Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution From $\forall x(P(x)\vee Q(x))$, we can get: $P(c)\vee Q(c)$ So, step (B) is correct. But from $P(c)\vee Q(c)$, we cannot conclude $P(c)$ alone. Also, we cannot conclude $Q(c)$ alone. So, steps (C) and (E) are not correct inferences. Step (G) would be correct only if (D) and (F) were validly obtained. Hence, the main error is in steps (C) and (E).
Qus : 9
UGC NET Computer Science PYQ 2020
4
Simplified expression/s for following Boolean function $F(A,B,C,D)=\sum(0,1,2,3,6,12,13,14,15)$ is/are (A) $A'B' + AB + A'C'D'$ (B) $A'B' + AB + A'CD'$ (C) $A'B' + AB + BC'D'$ (D) $A'B' + AB + BCD'$ Choose the correct answer from the options given below:
1
(A) only 2
(B) only 3
(A) and (B) only 4
(B) and (D) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Given minterms are: $0,1,2,3,6,12,13,14,15$ $A'B'$ covers minterms $0,1,2,3$ $AB$ covers minterms $12,13,14,15$ Remaining minterm is $6$ Option (B): $A'CD'$ covers minterms $2,6$ Both are present in the function. So, option (B) is correct. Option (D): $BCD'$ covers minterms $6,14$ Both are present in the function. So, option (D) is also correct. Options (A) and (C) include minterm $4$, which is not present in the function.
Qus : 10
UGC NET Computer Science PYQ 2020
1
Which of the following statements with respect to K-segment pipelining are true? (A) Maximum speedup that a pipeline can provide is k theoretically. (B) It is impossible to achieve maximum speedup k in k-segment pipeline. (C) All segments in pipeline take same time in computation. Choose the correct answer from the options given below:
1
(A) and (B) only 2
(B) and (C) only 3
(A) and (C) only 4
(A), (B) and (C) Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution In a k-segment pipeline, theoretical maximum speedup is $k$. So, statement A is true. In practical cases, due to pipeline filling time, emptying time, delays and unequal stages, exact maximum speedup $k$ is not achieved. So, statement B is true. All pipeline segments need not take exactly the same computation time. So, statement C is false.
Qus : 11
UGC NET Computer Science PYQ 2020
3
Which of the following statements with respect to multiprocessor system are true? (A) Multiprocessor system is controlled by one operating system. (B) In Multiprocessor system, multiple computers are connected by the means of communication lines. (C) Multiprocessor system is classified as multiple instruction stream and multiple data stream system. Choose the correct answer from the options given below:
1
(A) only 2
(A) and (B) only 3
(A) and (C) only 4
(B) and (C) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution A multiprocessor system has multiple processors controlled by one operating system. So, statement A is true. Multiple computers connected through communication lines describes a distributed system or multicomputer system, not a tightly coupled multiprocessor system. So, statement B is false. Multiprocessor systems are generally classified as MIMD systems, that means multiple instruction stream and multiple data stream. So, statement C is true. Therefore, A and C only are correct.
Qus : 12
UGC NET Computer Science PYQ 2020
3
Which of the following statements regarding XML is/are True? (A) XML is a set of tags designed to tell browsers how to display text and images in a web page. (B) XML defines a syntax for representing data, but the meaning of data varies from application to application. (C) <Letter>, <LETTER>, and <letter> are three different tags in XML. Choose the correct answer from the options given below:
1
(A) and (B) only 2
(A) and (C) only 3
(B) and (C) only 4
(A), (B) and (C) Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution XML is used to store and transport data, not to display data like HTML. So, statement A is false. XML defines syntax for representing data, but meaning depends on application. So, statement B is true. XML tags are case-sensitive. So, <Letter>, <LETTER>, and <letter> are different tags. So, statement C is true.
Qus : 13
UGC NET Computer Science PYQ 2020
1
In the context of 3D Computer graphics, which of the following statements is/are correct? (A) Under perspective projection, each set of parallel lines in the object do not stay parallel in the image except those that are parallel to the viewplane to start with. (B) Applying a perspective transformation in the graphics pipeline to a vertex involves dividing by its z coordinate. (C) Perspective transformation is a linear transformation. Choose the correct answer from the options given below:
1
(A) and (B) only 2
(A) and (C) only 3
(B) and (C) only 4
(A), (B) and (C) Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution In perspective projection, parallel lines generally meet at vanishing point. So, statement A is true. Perspective transformation involves perspective division, commonly by z-coordinate. So, statement B is true. Because division is involved, perspective transformation is not linear. So, statement C is false.
Qus : 14
UGC NET Computer Science PYQ 2020
3
Concerning Phong shading and Gouraud shading in a 3D scene, which of the following statements are true? (A) Gouraud shading requires more computation than Phong shading. (B) Gouraud shading linearly interpolates the color of an interior pixel from the color at the vertices. (C) Phong shading interpolates over the normal vectors specified at the vertices. Choose the correct answer from the options given below:
1
(A) and (B) only 2
(A) and (C) only 3
(B) and (C) only 4
(A), (B) and (C) Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Phong shading requires more computation than Gouraud shading. So, statement A is false. Gouraud shading computes color at vertices and interpolates color inside the polygon. So, statement B is true. Phong shading interpolates normal vectors and then computes illumination. So, statement C is true.
Qus : 15
UGC NET Computer Science PYQ 2020
2
In the context of concurrency control, a given pair of operations in a schedule is called conflict schedule if (A) At least one of the operations is write operation. (B) Both the operations are performed on the same data item. (C) Both the operations are performed by different transactions. (D) Both the operations are performed on different data items. Choose the correct answer from the options given below:
1
(A) and (B) only 2
A), (B) and (C) only 3
(A), (C) and (D) only 4
(C) and (D) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Two operations conflict if: They belong to different transactions. They operate on the same data item. At least one operation is write. So, statements A, B and C are true. Statement D is false because conflict needs same data item, not different data items.
Qus : 17
UGC NET Computer Science PYQ 2020
1
To create an object-behavioral model, the analyst performs the following steps: (A) Evaluates all use-cases (B) Builds state transition diagram for the system. (C) Reviews the object behaviour model to verify accuracy and consistency (D) Identifies events that do not derive the interaction sequence. Choose the correct answer from the options given below:
1
(A), (B) and (C) only 2
(A), (B) and (D) only 3
(B), (C) and (D) only 4
(A), (C) and (D) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution For object-behavioral modeling, analyst evaluates use-cases. State transition diagram is also built to show object states and transitions. The model is reviewed for accuracy and consistency. Statement D is not correct as written, because events should drive the interaction sequence, not “do not derive” it.
Qus : 18
UGC NET Computer Science PYQ 2020
2
Which of the following is/are behavioral testing technique(s)? (A) Equivalence Partitioning (B) Graph-Based Testing Method (C) Boundary Value Analysis (D) Data flow Testing (E) Loop Testing Choose the correct answer from the options given below:
1
(B) and (D) only 2
(A), (B) and (C) only 3
(D) and (E) only 4
(A), (C) and (E) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Behavioral testing means black-box testing. Equivalence partitioning is a black-box testing technique. Graph-based testing method is also a behavioral testing technique. Boundary value analysis is also a black-box testing technique. Data flow testing and loop testing are white-box testing techniques. Therefore, A, B and C only are correct.
Qus : 19
UGC NET Computer Science PYQ 2020
1
The running time of an algorithm is $O(g(n))$ if and only if: (A) its worst-case running time is $O(g(n))$ and its best-case running time is $\Omega(g(n))$. (B) its worst-case running time is $\Omega(g(n))$ and its best-case running time is $O(g(n))$. (C) $O(g(n))=\Omega(g(n))$. (D) $o(g(n))\cap \omega(g(n))$ is non-empty. Choose the correct answer from the options given below:
1
(A) only 2
(B) only 3
(C) only 4
(D) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution For an algorithm to have tight running time $\Theta(g(n))$, worst-case should be $O(g(n))$ and best-case should be $\Omega(g(n))$. This condition is given in statement A. Statement B reverses the required bounds. Statement C is false because $O(g(n))$ and $\Omega(g(n))$ are not always equal. Statement D is false because a function cannot be both smaller order and larger order than the same $g(n)$.
Qus : 20
UGC NET Computer Science PYQ 2020
3
Consider the following statements: (A) Any tree is 2-colorable (B) A graph G has no cycles of even length if it is bipartite. (C) A graph G is 2-colorable if it is bipartite. (D) A graph G can be colored with d+1 colors if d is the maximum degree of any vertex in the graph G. (E) A graph G can be colored with O(log|V|) colors if it has O(|V|) edges. Choose the correct answer from the options given below:
1
(C) and (E) are incorrect 2
(B) and (C) are incorrect 3
(B) and (E) are incorrect 4
(A) and (D) are incorrect Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution (A) True, because every tree is bipartite, so it is 2-colorable. (B) False, because a bipartite graph has no odd cycle, but it can have even cycles. (C) True, because every bipartite graph is 2-colorable. (D) True, by greedy coloring, any graph with maximum degree $d$ can be colored using at most $d+1$ colors. (E) False, because having $O(|V|)$ edges does not guarantee coloring with only $O(\log |V|)$ colors. So, incorrect statements are (B) and (E).
Qus : 21
UGC NET Computer Science PYQ 2020
3
Which among the following statement(s) is (are) true? (A) A hash function takes a message of arbitrary length and generates a fixed length code. (B) A hash function takes a message of fixed length and generates a code of variable length. (C) A hash function may give same hash value for distinct messages. Choose the correct answer from the options given below:
1
(A) only 2
(B) and (C) only 3
(A) and (C) only 4
(B) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution A hash function takes an input message of arbitrary length and produces a fixed length hash value. So, statement (A) is true. Statement (B) is false because hash function output is fixed length, not variable length. Statement (C) is true because two different messages may produce the same hash value. This is called collision. Therefore, true statements are (A) and (C) only.
Qus : 22
UGC NET Computer Science PYQ 2020
4
Let $G_1$ and $G_2$ be arbitrary context free languages and $R$ an arbitrary regular language. Consider the following problems: $(A)$ Is $L(G_1)=L(G_2)$? $(B)$ Is $L(G_2)\subseteq L(G_1)$? $(C)$ Is $L(G_1)=R$? Which of the problems are undecidable?
1
(A) only 2
(B) and (C) only 3
(A) and (C) only 4
(B) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution For context free languages, equivalence problem is undecidable. So, $L(G_1)=L(G_2)$ is undecidable. Also, inclusion problem for context free languages is undecidable. So, $L(G_2)\subseteq L(G_1)$ is undecidable. Now, $L(G_1)=R$ is also undecidable because if $R=\Sigma^*$, then this becomes CFL universality problem: $L(G_1)=\Sigma^*$ which is undecidable. Therefore, all three problems are undecidable.
Qus : 23
UGC NET Computer Science PYQ 2020
4
Consider the following languages: $L_1=\{a^{2^z}\mid z\text{ is an integer}\}$ $L_2=\{a^{2z}\mid z\ge 0\}$ $L_3=\{\omega\omega\mid \omega\in\{a,b\}^*\}$ Which of the languages is or are regular? Choose the correct answer from the options given below:
1
$L_1$ and $L_2$ only 2
$L_1$ and $L_3$ only 3
$L_1$ only 4
$L_2$ only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution For $L_1$: $L_1=\{a^{2^z}\mid z\text{ is an integer}\}$ The possible lengths are: $1,2,4,8,16,32,\ldots$ So, $L_1=\{a,a^2,a^4,a^8,a^{16},\ldots\}$ This is not regular because the gap between consecutive string lengths keeps increasing. So, $L_1$ is not regular. For $L_2$: $L_2=\{a^{2z}\mid z\ge 0\}$ The possible lengths are: $0,2,4,6,8,\ldots$ So, $L_2=\{\lambda,a^2,a^4,a^6,\ldots\}$ This language contains all strings of even length over alphabet $\{a\}$. It can be written as: $L_2=(aa)^*$ Since $(aa)^*$ is a regular expression, $L_2$ is regular. For $L_3$: $L_3=\{\omega\omega\mid \omega\in\{a,b\}^*\}$ In this language, the second half of the string must be exactly the same as the first half. A finite automaton cannot remember the complete first half and compare it with the second half. So, $L_3$ is not regular. Therefore, only $L_2$ is regular.
Qus : 24
UGC NET Computer Science PYQ 2020
1
Which of the following grammars is or are ambiguous? $(A)\ S\rightarrow SS\mid aSb\mid bSa\mid \lambda$ $(B)\ S\rightarrow aSbS\mid bSaS\mid \lambda$ $(C)\ S\rightarrow aAB$ $A\rightarrow bBb$ $B\rightarrow A\mid \lambda$ where $\lambda$ denotes empty string. Choose the correct answer from the options given below:
1
$(A)$ and $(C)$ and (C) only 2
$(B)$ only 3
$(B)$ and $(C)$ only 4
$(A)$ and $(B)$ only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution A grammar is ambiguous if at least one string has more than one parse tree or more than one leftmost derivation. For grammar $(A)$: $S\rightarrow SS\mid aSb\mid bSa\mid \lambda$ The string $abab$ can be generated in more than one way. First derivation: $S\Rightarrow SS$ $\Rightarrow aSbS$ $\Rightarrow abS$ $\Rightarrow abaSb$ $\Rightarrow abab$ Second derivation: $S\Rightarrow aSb$ $\Rightarrow abSab$ $\Rightarrow abab$ So, grammar $(A)$ is ambiguous. For grammar $(B)$: $S\rightarrow aSbS\mid bSaS\mid \lambda$ The string $abab$ can be generated in more than one way. First derivation: $S\Rightarrow aSbS$ $\Rightarrow abS$ $\Rightarrow abaSbS$ $\Rightarrow abab$ Second derivation: $S\Rightarrow aSbS$ $\Rightarrow a(bSaS)bS$ $\Rightarrow abab$ So, grammar $(B)$ is ambiguous. For grammar $(C)$: $S\rightarrow aAB$ $A\rightarrow bBb$ $B\rightarrow A\mid \lambda$ The string $abbbb$ can be generated in two ways. First way: $S\Rightarrow aAB$ $\Rightarrow a(bb)(bb)$ $\Rightarrow abbbb$ Second way: $S\Rightarrow aAB$ $\Rightarrow a(bbbb)(\lambda)$ $\Rightarrow abbbb$ So, grammar $(C)$ is also ambiguous. Therefore, grammars $(A)$, $(B)$ and $(C)$ all are ambiguous.
Qus : 25
UGC NET Computer Science PYQ 2020
1
Which of the following cloud concept or concepts is or are related to pooling and sharing of resources? $(A)$ Virtual Memory $(B)$ Service $(C)$ Virtualization Choose the correct answer from the options given below:
1
$(C)$ only 2
$(A)$ and $(B)$ only 3
$(A)$ only 4
$(B)$ only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution In cloud computing, pooling and sharing of resources means multiple users can use shared computing resources like CPU, memory, storage and network. Virtualization is the main concept that helps in pooling and sharing of resources. Using virtualization, one physical machine can be divided into multiple virtual machines. So, many users can share the same physical resources. Virtual Memory is an operating system concept, not mainly a cloud computing concept for resource pooling. Service means providing facilities like $IaaS$, $PaaS$ and $SaaS$, but the direct concept related to pooling and sharing is virtualization. Therefore, only $(C)$ Virtualization is correct.
Qus : 26
UGC NET Computer Science PYQ 2020
4
Post office protocol $(POP)$ is a message access protocol which is used to extract message for client. In this regard, which of the following are true? $(A)$ POP has two modes, Delete mode and keep mode $(B)$ In Delete mode, mail is deleted from mail box after each retrieval $(C)$ In Delete mode, mail is deleted from mail box before each retrieval $(D)$ In keep mode, mail is deleted before retrieval $(E)$ In keep mode, mail remains in mail box after retrieval Choose the correct answer from the options given below:
1
$(A)$ and $(B)$ only 2
$(A)$, $(D)$ and $(E)$ only 3
$(A)$, $(B)$, $(C)$ and $(E)$ only 4
$(A)$, $(B)$ and $(E)$ only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution POP is used by a client to download emails from the mail server. POP has two modes: Delete mode and keep mode. In Delete mode, after the client retrieves the mail, the mail is deleted from the mailbox. So, statement $(B)$ is true. In Delete mode, mail is not deleted before retrieval. So, statement $(C)$ is false. In keep mode, mail is not deleted after retrieval. The mail remains in the mailbox even after retrieval. So, statement $(E)$ is true. Statement $(D)$ is false because in keep mode mail is not deleted before retrieval. Therefore, true statements are $(A)$, $(B)$ and $(E)$.
Qus : 27
UGC NET Computer Science PYQ 2020
4
Firewall is a device that filters access to the protected network from the outside network. Firewalls can filter the packets on the basis of (A) Source IP Address (B) Destination IP Address (C) TCP Source Port (D) UDP Source Port (E) TCP Destination Port Choose the correct answer from the options given below:
1
(A), (B) and (C) only 2
(B) and (E) only 3
(C) and (D) only 4
(A), (B), (C), (D) and (E) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution A firewall can filter packets using information present in the packet header. It can filter packets on the basis of Source IP Address. So, statement (A) is true. It can filter packets on the basis of Destination IP Address. So, statement (B) is true. It can filter packets on the basis of TCP Source Port. So, statement (C) is true. It can filter packets on the basis of UDP Source Port. So, statement (D) is true. It can also filter packets on the basis of TCP Destination Port. So, statement (E) is true. Therefore, all statements (A), (B), (C), (D) and (E) are correct.
Qus : 28
UGC NET Computer Science PYQ 2020
4
Consider the statement below. A person who is radical $(R)$ is electable $(E)$ if he or she is conservative $(C)$, but otherwise is not electable. Few probable logical assertions of the above sentence are given below. (A) $(R\land E)\Leftrightarrow C$ (B) $R\Rightarrow(E\Leftrightarrow C)$ (C) $R\Rightarrow((C\Rightarrow E)\lor \neg E)$ (D) $(\neg R\lor \neg E\lor C)\land(\neg R\lor \neg C\lor E)$ Which of the above logical assertions are true? Choose the correct answer from the options given below:
1
(B) only 2
(C) only 3
(A) and (C) only 4
(B) and (D) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Given statement says that a radical person is electable if he or she is conservative, otherwise not electable. This means, for a radical person, electability depends exactly on conservativeness. So, the correct logical form is: $R\Rightarrow(E\Leftrightarrow C)$ Therefore, statement (B) is true. Now, $E\Leftrightarrow C$ can be written as: $(E\Rightarrow C)\land(C\Rightarrow E)$ So, $R\Rightarrow[(E\Rightarrow C)\land(C\Rightarrow E)]$ Now convert implications: $E\Rightarrow C\equiv \neg E\lor C$ $C\Rightarrow E\equiv \neg C\lor E$ Therefore, $R\Rightarrow[(\neg E\lor C)\land(\neg C\lor E)]$ This is equivalent to: $(\neg R\lor \neg E\lor C)\land(\neg R\lor \neg C\lor E)$ So, statement (D) is also true. Statement (A) is not correct because it says that a person is conservative if and only if the person is radical and electable, which is not the meaning of the given sentence. Statement (C) is not the exact logical assertion of the given sentence. Therefore, correct statements are (B) and (D).
Qus : 29
UGC NET Computer Science PYQ 2020
4
Which of the following statements are true? (A) A sentence $\alpha$ entails another sentence $\beta$ if $\beta$ is true in few worlds where $\alpha$ is true. (B) Forward chaining and backward chaining are very natural reasoning algorithms for knowledge bases in Horn form. (C) Sound inference algorithms derive all sentences that are entailed. (D) Propositional logic does not scale to environments of unbounded size. Choose the correct answer from the options given below:
1
(A) and (B) only 2
(B) and (C) only 3
(C) and (D) only 4
(B) and (D) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Statement (A) is false. Entailment means if $\alpha$ is true, then $\beta$ must be true in all models where $\alpha$ is true. Correct definition is: $\alpha\models\beta$ means $\beta$ is true in every model in which $\alpha$ is true. But statement (A) says few worlds, so it is false. Statement (B) is true. Forward chaining and backward chaining are natural reasoning algorithms for Horn form knowledge bases. Statement (C) is false. Sound inference algorithm derives only those sentences that are logically entailed. But deriving all entailed sentences is the property of completeness, not soundness. Statement (D) is true. Propositional logic does not scale well to environments of unbounded size because it cannot represent general rules using variables and quantifiers. Therefore, true statements are (B) and (D).
Qus : 30
UGC NET Computer Science PYQ 2020
3
Which of the following statements are true? (A) Minimax search is breadth-first; it processes all the nodes at a level before moving to a node in next level. (B) The effectiveness of the alpha-beta pruning is highly dependent on the order in which the states are examined. (C) The alpha-beta search algorithm computes the same optimal moves as minimax algorithm. (D) Optimal play in games of imperfect information does not require reasoning about the current and future belief states of each player. Choose the correct answer from the options given below:
1
(A) and (C) only 2
(A) and (D) only 3
(B) and (C) only 4
(C) and (D) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Minimax search is generally implemented using depth-first search, not breadth-first search. Statement (B) is true. Alpha-beta pruning depends highly on the order in which states are examined. If the best moves are examined first, more pruning is possible. Statement (C) is true. Alpha-beta pruning does not change the final result of minimax. It only reduces the number of nodes examined. So, alpha-beta search computes the same optimal move as minimax. Statement (D) is false. In games of imperfect information, optimal play requires reasoning about current and future belief states of each player. Therefore, true statements are (B) and (C).
Qus : 31
UGC NET Computer Science PYQ 2020
4
Match List I with List II.Let $R_1=\{(1,1),(2,2),(3,3)\}$ and$R_2=\{(1,1),(1,2),(1,3),(1,4)\}$
List I
List II
(A) $R_1\cup R_2$
I. $\{(1,1),(1,2),(1,3),(1,4),(2,2),(3,3)\}$
(B) $R_1-R_2$
II. $\{(1,1)\}$
(C) $R_1\cap R_2$
III. $\{(1,2),(1,3),(1,4)\}$
(D) $R_2-R_1$
IV. $\{(2,2),(3,3)\}$
Choose the correct answer from the options given below:
1
A-I, B-II, C-IV, D-III 2
A-I, B-IV, C-III, D-II 3
A-I, B-III, C-II, D-IV 4
A-I, B-IV, C-II, D-III Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Given, $R_1=\{(1,1),(2,2),(3,3)\}$ $R_2=\{(1,1),(1,2),(1,3),(1,4)\}$ Now, $R_1\cup R_2$ means all elements of $R_1$ and $R_2$. So, $R_1\cup R_2=\{(1,1),(1,2),(1,3),(1,4),(2,2),(3,3)\}$ Therefore, (A) matches with I. Now, $R_1-R_2$ means elements that are in $R_1$ but not in $R_2$. Common element is $(1,1)$. So, $R_1-R_2=\{(2,2),(3,3)\}$ Therefore, (B) matches with IV. Now, $R_1\cap R_2$ means common elements of $R_1$ and $R_2$. So, $R_1\cap R_2=\{(1,1)\}$ Therefore, (C) matches with II. Now, $R_2-R_1$ means elements that are in $R_2$ but not in $R_1$. So, $R_2-R_1=\{(1,2),(1,3),(1,4)\}$ Therefore, (D) matches with III. Final matching is: A-I, B-IV, C-II, D-III
Qus : 32
UGC NET Computer Science PYQ 2020
3
Match List I with List II.
List I List II (A) Handshaking (I) I/O interface informs the CPU that device is ready for transfer (B) Programmed I/O (II) Requires two control signals working in opposite directions (C) Interrupt-initiated I/O (III) Has local memory and controls large set of I/O devices (D) I/O processor (IV) Requires CPU to check the I/O flag and perform transfer
Choose the correct answer from the options given below:
1
A-I, B-II, C-III, D-IV 2
A-II, B-IV, C-III, D-I 3
A-II, B-IV, C-I, D-III 4
A-IV, B-III, C-II, D-I Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Handshaking requires two control signals working in opposite directions. So, (A) matches with II. Programmed I/O requires the CPU to continuously check the I/O flag and perform the transfer. So, (B) matches with IV. In interrupt-initiated I/O, the I/O interface informs the CPU that the device is ready for transfer. So, (C) matches with I. An I/O processor has local memory and controls a large set of I/O devices. So, (D) matches with III. Final matching is: A-II, B-IV, C-I, D-III
Qus : 33
UGC NET Computer Science PYQ 2020
4
Match List-I with List-II.List I gives $3\times 3$ matrices representing $2D$ transformations and List-II shows the corresponding transformation diagrams.
Choose the correct answer from the options given below:
1
A-IV, B-II, C-III, D-I 2
A-IV, B-III, C-II, D-I 3
A-III, B-II, C-IV, D-I 4
A-II, B-IV, C-III, D-I Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution For (A), $\left[[2,0,0],[0,2,0],[0,0,1]\right]$ This is a scaling matrix. Here, $S_x=2$ and $S_y=2$. So, (A) matches with (II). For (B), $\left[[1,0,2],[0,1,2],[0,0,1]\right]$ This is a translation matrix. Here, $T_x=2$ and $T_y=2$. So, (B) matches with (IV). For (C), $\left[[0.5,-0.866,0],[0.866,0.5,0],[0,0,1]\right]$ The standard rotation matrix is: $\left[[\cos\theta,-\sin\theta,0],[\sin\theta,\cos\theta,0],[0,0,1]\right]$ Here, $\cos 60^\circ=0.5$ and $\sin 60^\circ=0.866$ So, this matrix represents rotation by $60^\circ$. Therefore, (C) matches with (III). For (D), $\left[[1,2,0],[0,1,0],[0,0,1]\right]$ This is shear in $x$ direction. Here, shear factor is $2$. So, (D) matches with (I). Final matching is: A-II, B-IV, C-III, D-I
Qus : 34
UGC NET Computer Science PYQ 2020
3
Match List I with List II.
Choose the correct answer from the options given below:
1
A-II, B-IV, C-III, D-I 2
A-IV, B-I, C-II, D-III 3
A-II, B-I, C-IV, D-III 4
A-III, B-IV, C-I, D-II Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution In E-R diagram, double rectangle represents weak entity type. So, (A) matches with (II). Oval with underlined attribute represents key attribute type. So, (B) matches with (I). Double oval represents multivalue attribute type. So, (C) matches with (IV). Double line between entity and relationship represents total participation of entity in a relation. So, (D) matches with (III). Final matching is: A-II, B-I, C-IV, D-III
Qus : 35
UGC NET Computer Science PYQ 2020
3
Match List I with List II.With reference to CMM developed by Software Engineering Institute (SEI)
List I List II (A) INITIAL (I) Process measurement (B) REPEATABLE (II) Process definition (C) DEFINED (III) Project management (D) MANAGED (IV) ADHOC
Choose the correct answer from the options given below:
1
A-III, B-IV, C-II, D-I 2
A-IV, B-III, C-I, D-II 3
A-IV, B-III, C-II, D-I 4
A-III, B-IV, C-I, D-II Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution CMM has different maturity levels. INITIAL level means the process is ad hoc. So, (A) matches with IV. REPEATABLE level focuses on project management. So, (B) matches with III. DEFINED level focuses on process definition. So, (C) matches with II. MANAGED level focuses on process measurement. So, (D) matches with I. Final matching is: A-IV, B-III, C-II, D-I
Qus : 36
UGC NET Computer Science PYQ 2020
1
Match List I with List II.
List I List II (A) Branch-and-bound (I) Keeps track of all partial paths which can be candidate for further exploration. (B) Steepest-accent hill climbing (II) Detects difference between current state and goal state. (C) Constraint satisfaction (III) Discover problem state(s) that satisfy a set of constraints. (D) Means-end-analysis (IV) Consider all moves from current state and select best move.
Choose the correct answer from the options given below:
1
A-I, B-IV, C-III, D-II 2
A-I, B-II, C-III, D-IV 3
A-II, B-I, C-III, D-IV 4
A-II, B-IV, C-III, D-I Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Branch-and-bound keeps track of partial paths which can be candidates for further exploration. So, (A) matches with I. Steepest-accent hill climbing considers all possible moves from the current state and selects the best move. So, (B) matches with IV. Constraint satisfaction means finding state or states that satisfy a given set of constraints. So, (C) matches with III. Means-end-analysis detects the difference between current state and goal state. So, (D) matches with II. Final matching is: A-I, B-IV, C-III, D-II
Qus : 37
UGC NET Computer Science PYQ 2020
3
Match List I with List II.
List I List II (A) Topological sort of DAG (I) $O(V+E)$ (B) Kruskal's MST algorithm (II) $O(VE)$ (C) Bellman-Ford's single-source shortest path algorithm (III) $\theta(V+E)$ (D) Floyd-Warshall's all pair shortest path algorithm (IV) $\theta(V^3)$
Choose the correct answer from the options given below:
1
A-I, B-III, C-IV, D-II 2
A-III, B-I, C-IV, D-II 3
A-III, B-I, C-II, D-IV 4
A-I, B-III, C-II, D-IV Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Topological sorting of a DAG takes $\theta(V+E)$ time. So, (A) matches with III. Bellman-Ford single-source shortest path algorithm takes $O(VE)$ time. So, (C) matches with II. Floyd-Warshall all pair shortest path algorithm takes $\theta(V^3)$ time. So, (D) matches with IV. Now, from the given matching list, Kruskal's MST algorithm is matched with $O(V+E)$. So, (B) matches with I. Final matching is: A-III, B-I, C-II, D-IV
Qus : 38
UGC NET Computer Science PYQ 2020
3
Match List I with List II.$L_R$ : Regular language, $L_{CF}$ : Context free language$L_{REC}$ : Recursive language, $L_{RE}$ : Recursively enumerable language.
List I List II (A) Recursively Enumerable language (I) $\overline{L_{REC}}\cup L_{RE}$ (B) Recursive language (II) $\overline{L_{CF}}\cup L_{REC}$ (C) Context Free language (III) $L_R^*\cap L_{CF}$
Choose the correct answer from the options given below:
1
A-II, B-III, C-I 2
A-III, B-I, C-II 3
A-I, B-II, C-III 4
A-II, B-I, C-III Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution For (I), $\overline{L_{REC}}\cup L_{RE}$ Recursive languages are closed under complement. So, $\overline{L_{REC}}$ is also recursive. Every recursive language is recursively enumerable. Union of a recursively enumerable language with a recursive language is recursively enumerable. So, (I) represents recursively enumerable language. Therefore, (A) matches with I. For (II), $\overline{L_{CF}}\cup L_{REC}$ Every context free language is recursive. Recursive languages are closed under complement. So, $\overline{L_{CF}}$ is recursive. Union of two recursive languages is recursive. So, (II) represents recursive language. Therefore, (B) matches with II. For (III), $L_R^*\cap L_{CF}$ Regular languages are closed under Kleene star. So, $L_R^*$ is regular. Intersection of a regular language with a context free language is context free. So, (III) represents context free language. Therefore, (C) matches with III. Final matching is: A-I, B-II, C-III
Qus : 39
UGC NET Computer Science PYQ 2020
2
Match List I with List II.
List I List II (A) Serial Line IP $(SLIP)$ (I) Application layer (B) Border Gateway Protocol $(BGP)$ (II) Transport layer (C) User Data Protocol $(UDP)$ (III) Data Link layer (D) Simple Network Management Protocol (IV) Network layer
Choose the correct answer from the options given below:
1
A-I, B-II, C-III, D-IV 2
A-III, B-IV, C-II, D-I 3
A-II, B-III, C-IV, D-I 4
A-III, B-I, C-IV, D-II Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Serial Line IP $(SLIP)$ is used for transmitting IP packets over serial links. It works at the Data Link layer. So, (A) matches with III. Border Gateway Protocol $(BGP)$ is used for routing between autonomous systems. So, it is associated with the Network layer. So, (B) matches with IV. User Data Protocol $(UDP)$ is a Transport layer protocol. So, (C) matches with II. Simple Network Management Protocol $(SNMP)$ is an Application layer protocol. So, (D) matches with I. Final matching is: A-III, B-IV, C-II, D-I
Qus : 40
UGC NET Computer Science PYQ 2020
1
Match List I with List II.
List I List II (A) Greedy Best-First Search (I) Space complexity is $O(d)$ where $d$ is depth of the deepest optimal solution. (B) $A^*$ (II) Incomplete even if the search space is finite. (C) Recursive Best-First Search (III) Optimal if the optimal solution is reachable; otherwise, returns the best reachable optimal solution. (D) $SMA^*$ (IV) Computation and space complexity are too high.
Choose the correct answer from the options given below:
1
A-II, B-IV, C-I, D-III 2
A-II, B-III, C-I, D-IV 3
A-III, B-II, C-IV, D-I 4
A-III, B-IV, C-II, D-I Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Greedy Best-First Search selects the node that appears closest to the goal according to heuristic value. It may get trapped and can be incomplete even if the search space is finite. So, (A) matches with II. $A^*$ search is optimal and complete under proper conditions, but its computation and space complexity are very high because it stores many generated nodes. So, (B) matches with IV. Recursive Best-First Search uses limited memory and its space complexity is linear in depth. So, (C) matches with I. $SMA^*$ means Simplified Memory-Bounded $A^*$. It is optimal if the optimal solution is reachable within available memory; otherwise, it returns the best reachable solution. So, (D) matches with III. Final matching is: A-II, B-IV, C-I, D-III
Qus : 41
UGC NET Computer Science PYQ 2020
2
In lexicographic ordering, comparison is done from left to right. Given order is: $0<1$ Now compare the given strings: $0001$ comes before $001$ because at the third position, $0<1$. So, $0001<001$ Now, $001<010$ because at the second position, $0<1$. Also, $010<0101$ because $010$ is a prefix of $0101$. Now compare $0101$ and $011$: First digit is same. Second digit is same. Third digit gives: $0<1$ So, $0101<011$ Therefore, the correct lexicographic order is: $0001<001<010<0101<011$
1
$001<010<011<0001<0101$ 2
$0001<001<010<0101<011$ 3
$0001<0101<001<010<011$ 4
$001<010<0001<0101<011$ Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Greedy Best-First Search selects the node that appears closest to the goal according to heuristic value. It may get trapped and can be incomplete even if the search space is finite. So, (A) matches with II. $A^*$ search is optimal and complete under proper conditions, but its computation and space complexity are very high because it stores many generated nodes. So, (B) matches with IV. Recursive Best-First Search uses limited memory and its space complexity is linear in depth. So, (C) matches with I. $SMA^*$ means Simplified Memory-Bounded $A^*$. It is optimal if the optimal solution is reachable within available memory; otherwise, it returns the best reachable solution. So, (D) matches with III. Final matching is: A-II, B-IV, C-I, D-III
Qus : 43
UGC NET Computer Science PYQ 2020
3
Given below are different properties of $3D$ projections from A-D. Identify the correct order on the basis of property true of: $(i)$ a perspective projection only, $(ii)$ an orthographic projection only, $(iii)$ both orthographic and projective transformations, $(iv)$ neither orthographic nor projective transformation, respectively. (A) Straight lines are mapped to straight lines. (B) Distances and angles are in general preserved. (C) Far away objects appear the same size as closer ones. (D) Requires homogeneous coordinates in order for it to be encoded into a linear transformation. Choose the correct answer from the options given below:
1
D, C, B, A 2
B, C, D, A 3
D, C, A, B 4
C, D, B, A Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution For perspective projection only: Perspective projection needs homogeneous coordinates to represent it using matrix form. So, $(i)$ matches with D. For orthographic projection only: In orthographic projection, far away objects appear the same size as closer objects. So, $(ii)$ matches with C. For both orthographic and projective transformations: Both transformations map straight lines to straight lines. So, $(iii)$ matches with A. For neither orthographic nor projective transformation: Distances and angles are not preserved in general by these projections. So, $(iv)$ matches with B. Final order is: D, C, A, B
Qus : 44
UGC NET Computer Science PYQ 2020
4
Arrange the following types of Cohesion from best to worst type. (A) Logical Cohesion (B) Sequential Cohesion (C) Communication Cohesion (D) Temporal Cohesion (E) Procedural Cohesion Choose the correct answer from the options given below:
1
$A\rightarrow D\rightarrow E\rightarrow C\rightarrow B$ 2
$A\rightarrow E\rightarrow D\rightarrow C\rightarrow B$ 3
$B\rightarrow E\rightarrow C\rightarrow D\rightarrow A$ 4
$B\rightarrow C\rightarrow E\rightarrow D\rightarrow A$ Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution The strength of cohesion from best to worst is generally: Functional Cohesion Sequential Cohesion Communication Cohesion Procedural Cohesion Temporal Cohesion Logical Cohesion Coincidental Cohesion Here, Functional Cohesion and Coincidental Cohesion are not given. So, from the given options, best to worst order is: Sequential Cohesion $\rightarrow$ Communication Cohesion $\rightarrow$ Procedural Cohesion $\rightarrow$ Temporal Cohesion $\rightarrow$ Logical Cohesion According to given symbols: $B\rightarrow C\rightarrow E\rightarrow D\rightarrow A$
Qus : 45
UGC NET Computer Science PYQ 2020
1
Consider the undirected graph below.
Using Prim's algorithm to construct a minimum spanning tree starting with node $a$, which one of the following sequences of edges represents a possible order in which the edges would be added to construct the minimum spanning tree?
1
$(a,b),(a,h),(g,h),(f,g),(c,f),(c,i),(c,d),(d,e)$ 2
$(a,b),(b,h),(g,h),(g,i),(c,i),(c,f),(c,d),(d,e)$ 3
$(a,b),(b,c),(c,i),(c,f),(f,g),(g,h),(c,d),(d,e)$ 4
$(a,b),(g,h),(g,f),(c,f),(c,i),(f,e),(b,c),(d,e)$ Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Using Prim's algorithm, we always select the minimum weight edge that connects the current tree with a new vertex.
Start from vertex $a$.
From $a$, possible edges are:
$(a,b)=4$
$(a,h)=8$
Minimum edge is:
$(a,b)=4$
So, first edge is $(a,b)$.
Now current tree is:
$\{a,b\}$
Possible crossing edges are:
$(a,h)=8$
$(b,c)=8$
$(b,h)=11$
Here, $(a,h)$ and $(b,c)$ both have the same minimum weight $8$.
So, there is a tie.
If we choose $(a,h)$, then the sequence can be:
$(a,b),(a,h),(g,h),(f,g),(c,f),(c,i),(c,d),(d,e)$
This matches option (A).
Now check option (A):
After adding $(a,h)$, minimum edge from tree to outside is:
$(h,g)=1$
Then,
$(g,f)=2$
Then,
$(f,c)=4$
Then,
$(c,i)=2$
Then,
$(c,d)=7$
Then,
$(d,e)=9$
So, option (A) is a valid possible order.
But because of the tie at weight $8$, we may also choose $(b,c)$ instead of $(a,h)$.
If we choose $(b,c)$, then the sequence can be:
$(a,b),(b,c),(c,i),(c,f),(f,g),(g,h),(c,d),(d,e)$
This matches option (C).
So, option (C) is also a valid possible order.
Option (B) is not correct because after $(a,b)$, edge $(b,h)=11$ cannot be selected since edges of weight $8$ are available.
Option (D) is not correct because $(g,h)$ cannot be selected immediately after $(a,b)$ as it does not connect the current tree to a new vertex.
Therefore, both options (A) and (C) are possible due to tie in Prim's algorithm.
Correct Answer: (A) and (C) both are possible
Note: If the question expects only one answer, then it is ambiguous because Prim's algorithm can give different valid edge orders when equal weight edges are present.
Qus : 46
UGC NET Computer Science PYQ 2020
2
Consider the following regular expressions: (a) $r=a(b+a)^*$ (b) $s=a(a+b)^+$ (c) $t=aa^*b$ Choose the correct answer from the options given below based on the relation between the languages generated by the regular expressions above:
1
$L(r)\subseteq L(s)\subseteq L(t)$ 2
$L(r)\supseteq L(s)\supseteq L(t)$ 3
$L(r)\supseteq L(t)\supseteq L(s)$ 4
$L(s)\supseteq L(t)\supseteq L(r)$ Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution For $r=a(b+a)^*$: This represents all strings over $\{a,b\}$ that start with $a$. So, $L(r)=\{a,aa,ab,aaa,aab,aba,\ldots\}$ For $s=a(a+b)^+$: Here, after first $a$, at least one more symbol from $\{a,b\}$ must be present. So, $s$ represents all strings over $\{a,b\}$ that start with $a$ and have length at least $2$. Therefore, $L(s)\subseteq L(r)$ For $t=aa^*b$: This represents strings of the form: $ab,aab,aaab,aaaab,\ldots$ So, every string of $L(t)$ starts with $a$ and has length at least $2$. Therefore, $L(t)\subseteq L(s)$ Hence, $L(r)\supseteq L(s)\supseteq L(t)$
Qus : 47
UGC NET Computer Science PYQ 2020
1
Given below are two statements: Statement I: $5$ divides $n^5-n$ whenever $n$ is a nonnegative integer. Statement II: $6$ divides $n^3-n$ whenever $n$ is a nonnegative integer. In the light of the above statements, choose the correct answer from the options given below:
1
Both Statement I and Statement II are correct 2
Both Statement I and Statement II are incorrect 3
Statement I is correct but Statement II is incorrect 4
Statement I is incorrect but Statement II is correct Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Statement I: We need to check whether $5$ divides $n^5-n$. By Fermat's theorem, $n^5\equiv n\pmod 5$ So, $n^5-n\equiv 0\pmod 5$ Therefore, $5$ divides $n^5-n$. So, Statement I is correct. Statement II: $n^3-n=n(n-1)(n+1)$ This is the product of three consecutive integers. In any three consecutive integers, one number is divisible by $3$ and at least one number is divisible by $2$. So, the product is divisible by $6$. Therefore, $6$ divides $n^3-n$. So, Statement II is also correct.
Qus : 48
UGC NET Computer Science PYQ 2020
1
Given below are two statements: Statement I: Hardwired control unit can be optimized to produce fast mode of operation. Statement II: Indirect addressing mode needs two memory reference to fetch the operand. In the light of the above statements, choose the correct answer from the options given below:
1
Both Statement I and Statement II are true 2
Both Statement I and Statement II are false 3
Statement I is correct but Statement II is false 4
Statement I is incorrect but Statement II is true Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Statement I is true. Hardwired control unit uses fixed logic circuits. So, it is faster than microprogrammed control unit and can be optimized for fast operation. Statement II is also true. In indirect addressing mode, the address field of the instruction contains the address of the memory location where the effective address is stored. So, first memory reference is used to get the effective address. Second memory reference is used to fetch the actual operand. Therefore, indirect addressing needs two memory references to fetch the operand.
Qus : 49
UGC NET Computer Science PYQ 2020
4
Given below are two statements: Statement I: Bezier curves are curves that interpolate all of their control points. Statement II: A cubic Bezier curve has four control points. In the light of the above statements, choose the correct answer from the options given below:
1
Both Statement I and Statement II are true 2
Both Statement I and Statement II are false 3
Statement I is correct but Statement II is false 4
Statement I is incorrect but Statement II is true Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Solution: Statement I is false. Bezier curves do not interpolate all of their control points. A Bezier curve passes through the first and last control points, but the intermediate control points generally control the shape of the curve. So, it does not pass through all control points. Statement II is true. A cubic Bezier curve has degree $3$. For a Bezier curve of degree $n$, number of control points is $n+1$. So, for cubic Bezier curve: $n+1=3+1=4$ Therefore, a cubic Bezier curve has four control points.
Qus : 50
UGC NET Computer Science PYQ 2020
3
Given below are two statements: If two variables $V_1$ and $V_2$ are used for clustering, then consider the following statements for $k$ means clustering with $k=3$. Statement I: If $V_1$ and $V_2$ have correlation of $1$, the cluster centroid will be in straight line. Statement II: If $V_1$ and $V_2$ have correlation of $0$, the cluster centroid will be in straight line. In the light of the above statements, choose the correct answer from the options given below:
1
Both Statement I and Statement II are true 2
Both Statement I and Statement II are false 3
Statement I is correct but Statement II is false 4
Statement I is incorrect but Statement II is true Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Statement I is true. If $V_1$ and $V_2$ have correlation $1$, then they have perfect positive linear relationship. So, all data points lie on a straight line. In $k$ means clustering, centroids are calculated as the mean of points in each cluster. Mean of points lying on a straight line also lies on the same straight line. Therefore, the cluster centroids will be in a straight line. Statement II is false. If $V_1$ and $V_2$ have correlation $0$, then there is no linear relationship between them. So, the data points are not necessarily on a straight line. Therefore, the cluster centroids will not necessarily be in a straight line.
Qus : 51
UGC NET Computer Science PYQ 2020
3
Assuming that the system call $fork()$ never fails, consider the following C programs $P1$ and $P2$ executed on a UNIX or Linux system:
Program $P1$ Program $P2$ /* P1 */int main() { fork(); fork(); fork(); print("Happy\n");} /* P2 */int main() { fork(); print("Happy\n"); fork(); print("Happy\n"); fork(); print("Happy\n");}
Statement I: $P1$ displays "Happy" $8$ times.Statement II: $P2$ displays "Happy" $12$ times.In the light of the above statements, choose the correct answer from the options given below:
1
Both Statement I and Statement II are true 2
Both Statement I and Statement II are false 3
Statement I is correct but Statement II is false 4
Statement I is incorrect but Statement II is true Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution For program $P1$: There are $3$ fork calls before the print statement. Each $fork()$ doubles the number of processes. So, total number of processes after $3$ fork calls is: $2^3=8$ Each process executes the print statement. Therefore, $P1$ displays "Happy" $8$ times. So, Statement I is true. For program $P2$: Initially, there is $1$ process. After first $fork()$: Number of processes $=2$ So, first print statement executes $2$ times. After second $fork()$: Number of processes $=4$ So, second print statement executes $4$ times. After third $fork()$: Number of processes $=8$ So, third print statement executes $8$ times. Total number of times "Happy" is printed: $2+4+8=14$ So, $P2$ displays "Happy" $14$ times, not $12$ times. Therefore, Statement II is false.
Qus : 52
UGC NET Computer Science PYQ 2020
1
Given below are two statements: Statement I: Quality control involves the series of inspections, reviews and tests used throughout the software process, to ensure each work product meets the requirements placed upon it. Statement II: Quality assurance consists of auditing and reporting functions of management. In the light of the above statements, choose the correct answer from the options given below:
1
Both Statement I and Statement II are true 2
Both Statement I and Statement II are false 3
Statement I is correct but Statement II is false 4
Statement I is incorrect but Statement II is true Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Statement I is true. Quality control is related to inspections, reviews and testing of software products. Its main purpose is to check whether the work product satisfies the given requirements or not. Statement II is also true. Quality assurance is a management activity. It includes auditing and reporting functions to ensure that proper software processes are being followed. Therefore, both statements are true.
Qus : 53
UGC NET Computer Science PYQ 2020
3
Let $G$ be a simple undirected graph, $T_D$ be a DFS tree on $G$, and $T_B$ be the BFS tree on $G$. Consider the following statements. Statement I: No edge of $G$ is a cross with respect to $T_D$. Statement II: For every edge $(u,v)$ of $G$, if $u$ is at depth $i$ and $v$ is at depth $j$ in $T_B$, then $|i-j|=1$. In the light of the above statements, choose the correct answer from the options given below:
1
Both Statement I and Statement II are true 2
Both Statement I and Statement II are false 3
Statement I is correct but Statement II is false 4
Statement I is incorrect but Statement II is true Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Statement I is true. In DFS of an undirected graph, there are no cross edges. Edges are generally tree edges or back edges. So, no edge of $G$ is a cross edge with respect to DFS tree $T_D$. Statement II is false. In BFS tree, for every edge $(u,v)$, the depths of $u$ and $v$ differ by at most $1$. So, the correct condition is: $|i-j|\le 1$ But the statement says: $|i-j|=1$ This is not always true because two adjacent vertices can also be at the same level in a BFS tree. Therefore, Statement I is true and Statement II is false.
Qus : 54
UGC NET Computer Science PYQ 2020
1
Given below are two statements: Statement I: The problem "Is $L_1\cap L_2=\phi$?" is undecidable for context sensitive languages $L_1$ and $L_2$. Statement II: The problem "Is $W\in L$?" is decidable for context sensitive language $L$, where $W$ is a string. In the light of the above statements, choose the correct answer from the options given below:
1
Both Statement I and Statement II are true 2
Both Statement I and Statement II are false 3
Statement I is correct but Statement II is false 4
Statement I is incorrect but Statement II is true Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Statement I is true. For context sensitive languages, the emptiness problem is undecidable. Since context sensitive languages are closed under intersection, checking whether: $L_1\cap L_2=\phi$ is also undecidable. So, Statement I is true. Statement II is also true. Membership problem for context sensitive languages is decidable. This is because context sensitive languages are accepted by Linear Bounded Automata, and for a fixed input there are only finitely many configurations. Therefore, we can decide whether $W\in L$ or not. So, both statements are true.
Qus : 55
UGC NET Computer Science PYQ 2020
1
Given below are two statements: Statement I: The laws of nature put two fundamental limits on the data rate of a channel. The H. Nyquist limit restricts the number of independent samples per second to twice the bandwidth in a noiseless channel. Statement II: Shannon's major result about noisy channel is that the maximum data rate of a channel whose bandwidth is $H$ Hz, and whose signal-to-noise ratio is $\frac{S}{N}$ is given by: Maximum number of bits/sec $=H\log_2\left(1+\frac{S}{N}\right)$ In the light of the above statements, choose the correct answer from the options given below:
1
Both Statement I and Statement II are true 2
Both Statement I and Statement II are false 3
Statement I is correct but Statement II is false 4
Statement I is incorrect but Statement II is true Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Statement I is true. Nyquist theorem gives the limit for a noiseless channel. It says that for a channel of bandwidth $H$, the maximum number of independent samples per second is $2H$. So, Statement I is true. Statement II is also true. Shannon capacity theorem gives the maximum data rate of a noisy channel as: $C=H\log_2\left(1+\frac{S}{N}\right)$ where $H$ is bandwidth and $\frac{S}{N}$ is signal-to-noise ratio. Therefore, both statements are true.
Qus : 56
UGC NET Computer Science PYQ 2020
1
Given below are two statements: Statement I: In Caesar Cipher each letter of Plain text is replaced by another letter for encryption. Statement II: The Diffie-Hellman algorithm is used for the exchange of secret keys. In the light of the above statements, choose the correct answer from the options given below:
1
Both Statement I and Statement II are true 2
Both Statement I and Statement II are false 3
Statement I is correct but Statement II is false 4
Statement I is incorrect but Statement II is true Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Statement I is true. Caesar Cipher is a substitution cipher. In Caesar Cipher, each letter of the plain text is replaced by another letter by shifting it by a fixed number of positions. So, Statement I is true. Statement II is also true. Diffie-Hellman algorithm is used for secure key exchange between two parties. It helps two users to agree on a common secret key over an insecure channel. So, Statement II is true. Therefore, both statements are true.
Qus : 57
UGC NET Computer Science PYQ 2020
4
Given below are two statements: Statement I: A genetic algorithm is a stochastic hill-climbing search in which a large population of states is maintained. Statement II: In nondeterministic environments, agents can apply AND-OR search to generate contingent plans that reach the goal regardless of which outcomes occur during execution. In the light of the above statements, choose the correct answer from the options given below:
1
Both Statement I and Statement II are true 2
Both Statement I and Statement II are false 3
Statement I is correct but Statement II is false 4
Statement I is incorrect but Statement II is true Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Statement I is incorrect. A genetic algorithm maintains a population of states, but it is generally considered a variant of stochastic beam search, not simple stochastic hill-climbing. Hill-climbing usually works with one current state, while genetic algorithm works with a population of states and uses selection, crossover and mutation. So, Statement I is false. Statement II is true. In nondeterministic environments, actions may have more than one possible outcome. AND-OR search is used to handle such situations. It generates contingent plans, where the next action depends on the outcome that actually occurs. So, Statement II is true. Therefore, Statement I is incorrect but Statement II is true.
Qus : 58
UGC NET Computer Science PYQ 2020
3
concern a disk with a sector size of $512$ bytes, $2000$ tracks per surface, $50$ sectors per track, five double-sided platters, and average seek time of $10$ milliseconds. If $T$ is the capacity of a track in bytes, and $S$ is the capacity of each surface in bytes, then $(T,S)=$ _____
1
$(50K,500000K)$ 2
$(25K,25000K)$ 3
$(25K,50000K)$ 4
$(40K,36000K)$ Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Sector size $=512$ bytes Number of sectors per track $=50$ So, capacity of one track is: $T=512\times 50$ $T=25600$ bytes Since, $1K=1024$ bytes So, $T=\frac{25600}{1024}=25K$ Now, each surface has $2000$ tracks. Capacity of each surface is: $S=25K\times 2000$ $S=50000K$ Therefore, $(T,S)=(25K,50000K)$
Qus : 59
UGC NET Computer Science PYQ 2020
2
concern a disk with a sector size of $512$ bytes, $2000$ tracks per surface, $50$ sectors per track, five double-sided platters, and average seek time of $10$ milliseconds. What is the capacity of the disk, in bytes?
1
$25,000K$ 2
$500,000K$ 3
$250,000K$ 4
$50,000K$ Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Given, Sector size $=512$ bytes Sectors per track $=50$ Tracks per surface $=2000$ Number of double-sided platters $=5$ So, number of surfaces: $5\times 2=10$ Capacity of one track: $512\times 50=25600$ bytes Since, $1K=1024$ bytes So, $\frac{25600}{1024}=25K$ Capacity of one surface: $25K\times 2000=50000K$ Capacity of total disk: $50000K\times 10=500000K$
Qus : 60
UGC NET Computer Science PYQ 2020
3
concern a disk with a sector size of $512$ bytes, $2000$ tracks per surface, $50$ sectors per track, five double-sided platters, and average seek time of $10$ milliseconds. Given below are two statements: Statement I: The disk has a total number of $2000$ cylinders. Statement II: $51200$ bytes is not a valid block size for the disk. In the light of the above statements, choose the correct answer from the options given below:
1
Both Statement I and Statement II are true 2
Both Statement I and Statement II are false 3
Statement I is correct but Statement II is false 4
Statement I is incorrect but Statement II is true Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Statement I is true. Number of cylinders is equal to the number of tracks per surface. Given, Tracks per surface $=2000$ So, total number of cylinders $=2000$. Therefore, Statement I is true. Statement II is false. Given sector size is: $512$ bytes A valid block size should be a multiple of sector size. Now, $51200=512\times 100$ So, $51200$ bytes is a valid block size. But Statement II says that $51200$ bytes is not a valid block size. Therefore, Statement II is false.
Qus : 61
UGC NET Computer Science PYQ 2020
1
concern a disk with a sector size of $512$ bytes, $2000$ tracks per surface, $50$ sectors per track, five double-sided platters, and average seek time of $10$ milliseconds. If the disk platters rotate at $5400$ rpm, then approximately what is the maximum rotational delay?
1
$0.011$ seconds 2
$0.11$ seconds 3
$0.0011$ seconds 4
$1.1$ seconds Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Given, Rotational speed $=5400$ rpm It means: $5400$ revolutions in $60$ seconds So, revolutions per second: $\frac{5400}{60}=90$ Time taken for one revolution: $\frac{1}{90}$ seconds $=0.0111$ seconds Maximum rotational delay is equal to time for one full revolution. So, maximum rotational delay is approximately: $0.011$ seconds
Qus : 62
UGC NET Computer Science PYQ 2020
4
concern a disk with a sector size of $512$ bytes, $2000$ tracks per surface, $50$ sectors per track, five double-sided platters, and average seek time of $10$ milliseconds. If one track of data can be transferred per revolution, then what is the data transfer rate?
1
$2,850$ KBytes/second 2
$4,500$ KBytes/second 3
$5,700$ KBytes/second 4
$2,250$ KBytes/second Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution From previous calculation, capacity of one track is: $25K$ bytes Given rotational speed: $5400$ rpm Revolutions per second: $\frac{5400}{60}=90$ If one track of data is transferred per revolution, then data transferred per second is: $25K\times 90$ $=2250K$ bytes/second So, data transfer rate is: $2250$ KBytes/second
Qus : 63
UGC NET Computer Science PYQ 2020
3
Consider the following table structures related to a university for the below questions.
EMPLOYEE
NAME
VARCHAR(30)
NOT NULL
EID
VARCHAR(10)
NOT NULL
DEPTNO
INT(5)
NOT NULL
HODEID
VARCHAR(10)
SALARY
INT(10)
PRIMARY KEY (EID),
FOREIGN KEY (HODEID) REFERENCES EMPLOYEE (EID),
FOREIGN KEY (DEPTNO) REFERENCES DEPARTMENT (DID);
DEPARTMENT
DID
INT(5)
NOT NULL
DNAME
VARCHAR(30)
NOT NULL
HODID
VARCHAR(10)
NOT NULL
HODNAME
VARCHAR(30)
PRIMARY KEY (DID),
UNIQUE (DNAME),
FOREIGN KEY (HODID) REFERENCES EMPLOYEE (EID);
PROJECT WORK
EMPID
VARCHAR(10)
NOT NULL
PROJNO
INT(5)
NOT NULL
PROJECTLOC
VARCHAR(30)
NOT NULL
PRIMARY KEY (EMPID, PROJNO),
FOREIGN KEY (EMPID) REFERENCES EMPLOYEE (EID);
On the basis of above given table structures, retrieve the distinct employee ID $(EMPID)$ of all employees of university who are working on project No. $20$, $30$ and $40$.
1
SELECT EMPIDFROM PROJECTWORKWHERE PROJNO=(20,30,40); 2
SELECT EMPIDFROM PROJECTWORKWHERE PROJNO IN (20,30,40); 3
SELECT DISTINCT EMPIDFROM PROJECTWORKWHERE PROJNO IN (20,30,40); 4
SELECT DISTINCT EMPIDFROM PROJECTWORKWHERE PROJNO=20,30,40; Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution We need to retrieve distinct employee IDs. So, we must use: SELECT DISTINCT EMPID Now, the project number can be $20$, $30$ or $40$. For checking multiple possible values in SQL, we use IN operator. So, correct condition is: WHERE PROJNO IN (20,30,40) Therefore, correct SQL query is: SELECT DISTINCT EMPID FROM PROJECTWORK WHERE PROJNO IN (20,30,40); Option (A) is incorrect because PROJNO=(20,30,40) is not valid SQL syntax. Option (B) is incorrect because it does not use DISTINCT. Option (D) is incorrect because PROJNO=20,30,40 is not valid SQL syntax. Correct Answer: (C) SELECT DISTINCT EMPID FROM PROJECTWORK WHERE PROJNO IN (20,30,40);
Qus : 64
UGC NET Computer Science PYQ 2020
3
Consider the following table structures related to a university for the below questions.
EMPLOYEE
NAME
VARCHAR(30)
NOT NULL
EID
VARCHAR(10)
NOT NULL
DEPTNO
INT(5)
NOT NULL
HODEID
VARCHAR(10)
SALARY
INT(10)
PRIMARY KEY (EID),
FOREIGN KEY (HODEID) REFERENCES EMPLOYEE (EID),
FOREIGN KEY (DEPTNO) REFERENCES DEPARTMENT (DID);
DEPARTMENT
DID
INT(5)
NOT NULL
DNAME
VARCHAR(30)
NOT NULL
HODID
VARCHAR(10)
NOT NULL
HODNAME
VARCHAR(30)
PRIMARY KEY (DID),
UNIQUE (DNAME),
FOREIGN KEY (HODID) REFERENCES EMPLOYEE (EID);
PROJECT WORK
EMPID
VARCHAR(10)
NOT NULL
PROJNO
INT(5)
NOT NULL
PROJECTLOC
VARCHAR(30)
NOT NULL
PRIMARY KEY (EMPID, PROJNO),
FOREIGN KEY (EMPID) REFERENCES EMPLOYEE (EID);
Given below are two statements to find the sum of salaries of all employees of the English department as well as the maximum, minimum and average salary in English department.
Statement I:
SELECT SUM(SALARY), MAX(SALARY), MIN(SALARY), AVG(SALARY)
FROM EMPLOYEE, DEPARTMENT
WHERE DEPTNO=DID
AND DNAME='ENGLISH';
Statement II:
SELECT SUM(SALARY), MAX(SALARY), MIN(SALARY), AVG(SALARY)
FROM EMPLOYEE, DEPARTMENT
WHERE DNAME='ENGLISH';
In the light of the above statements, choose the correct answer from the options given below:
1
Both Statement I and Statement II are true 2
Both Statement I and Statement II are false 3
Statement I is correct but Statement II is false 4
Statement I is incorrect but Statement II is true Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution We need to find salary details of employees who belong to the English department. For this, EMPLOYEE table and DEPARTMENT table must be joined. In Statement I: DEPTNO=DID This condition joins EMPLOYEE table with DEPARTMENT table. Also, DNAME='ENGLISH' filters only English department employees. So, Statement I is correct. In Statement II: Only condition is: DNAME='ENGLISH' There is no join condition between EMPLOYEE and DEPARTMENT. So, it will not correctly connect employees with their department. It may produce incorrect result due to Cartesian product. Therefore, Statement II is false.
Qus : 65
UGC NET Computer Science PYQ 2020
3
Consider the following table structures related to a university for the below questions.
EMPLOYEE
NAME
VARCHAR(30)
NOT NULL
EID
VARCHAR(10)
NOT NULL
DEPTNO
INT(5)
NOT NULL
HODEID
VARCHAR(10)
SALARY
INT(10)
PRIMARY KEY (EID),
FOREIGN KEY (HODEID) REFERENCES EMPLOYEE (EID),
FOREIGN KEY (DEPTNO) REFERENCES DEPARTMENT (DID);
DEPARTMENT
DID
INT(5)
NOT NULL
DNAME
VARCHAR(30)
NOT NULL
HODID
VARCHAR(10)
NOT NULL
HODNAME
VARCHAR(30)
PRIMARY KEY (DID),
UNIQUE (DNAME),
FOREIGN KEY (HODID) REFERENCES EMPLOYEE (EID);
PROJECT WORK
EMPID
VARCHAR(10)
NOT NULL
PROJNO
INT(5)
NOT NULL
PROJECTLOC
VARCHAR(30)
NOT NULL
PRIMARY KEY (EMPID, PROJNO),
FOREIGN KEY (EMPID) REFERENCES EMPLOYEE (EID);
Which of the following query or queries return the employee ID and name of employees whose salary is greater than the salary of all employees in department number $20$ of university?
Order results by employee ID.
(A)
SELECT EID, NAME
FROM EMPLOYEE
WHERE SALARY > (SELECT SALARY FROM EMPLOYEE WHERE DEPTNO = 20)
ORDER BY EID;
(B)
SELECT EID, NAME
FROM EMPLOYEE
WHERE SALARY > (SELECT SALARY FROM EMPLOYEE WHERE DEPTNO = 20);
(C)
SELECT EID, NAME
FROM EMPLOYEE
WHERE SALARY > ALL (SELECT SALARY FROM EMPLOYEE WHERE DEPTNO = 20)
ORDER BY EID;
Choose the correct answer from the options given below:
1
(A) and (B) only 2
(A) and (C) only 3
(B) only 4
(C) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution We need employees whose salary is greater than the salary of all employees in department number $20$. For comparing one value with all values returned by a subquery, we use: SALARY > ALL (subquery) So, the correct condition is: SALARY > ALL (SELECT SALARY FROM EMPLOYEE WHERE DEPTNO = 20) Also, the question asks to order results by employee ID. So, ORDER BY EID is also required. Option (A) is incorrect because the subquery may return more than one salary value. So, direct comparison using $>$ is not correct. Option (B) is incorrect because it also uses direct comparison with a subquery that may return multiple values, and it does not use ORDER BY EID. Option (C) is correct because it uses ALL and also orders the result by EID. Therefore, only query (C) is correct.
Qus : 66
UGC NET Computer Science PYQ 2020
1
Consider the following table structures related to a university for the below questions.
EMPLOYEE
NAME
VARCHAR(30)
NOT NULL
EID
VARCHAR(10)
NOT NULL
DEPTNO
INT(5)
NOT NULL
HODEID
VARCHAR(10)
SALARY
INT(10)
PRIMARY KEY (EID),
FOREIGN KEY (HODEID) REFERENCES EMPLOYEE (EID),
FOREIGN KEY (DEPTNO) REFERENCES DEPARTMENT (DID);
DEPARTMENT
DID
INT(5)
NOT NULL
DNAME
VARCHAR(30)
NOT NULL
HODID
VARCHAR(10)
NOT NULL
HODNAME
VARCHAR(30)
PRIMARY KEY (DID),
UNIQUE (DNAME),
FOREIGN KEY (HODID) REFERENCES EMPLOYEE (EID);
PROJECT WORK
EMPID
VARCHAR(10)
NOT NULL
PROJNO
INT(5)
NOT NULL
PROJECTLOC
VARCHAR(30)
NOT NULL
PRIMARY KEY (EMPID, PROJNO),
FOREIGN KEY (EMPID) REFERENCES EMPLOYEE (EID);
In reference to the above given table structures, which of the following query or queries will drop the 'SALARY' column from 'EMPLOYEE' table?
(A)
ALTER TABLE EMPLOYEE DROP SALARY CASCADE;
(B)
ALTER TABLE EMPLOYEE DROP SALARY RESTRICT;
(C)
ALTER EMPLOYEE DROP SALARY;
Choose the correct answer from the options given below::
1
(A) and (B) only 2
(A) and (C) only 3
(B) and (C) only 4
(A) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution To drop a column from a table, correct SQL syntax is: ALTER TABLE table_name DROP column_name; In Statement (A): ALTER TABLE EMPLOYEE DROP SALARY CASCADE; This query is valid because it uses ALTER TABLE and drops the SALARY column. CASCADE means if there are dependent objects, they may also be removed. So, Statement (A) is correct. In Statement (B): ALTER TABLE EMPLOYEE DROP SALARY RESTRICT; This query is also valid because it uses ALTER TABLE and drops the SALARY column. RESTRICT means the column will be dropped only if there is no dependent object. Here, SALARY is not used as a primary key or foreign key. So, Statement (B) is also correct. In Statement (C): ALTER EMPLOYEE DROP SALARY; This query is incorrect because the keyword TABLE is missing. Correct syntax should have ALTER TABLE, not only ALTER. So, Statement (C) is incorrect. Therefore, correct queries are (A) and (B) only.
Qus : 67
UGC NET Computer Science PYQ 2020
2
Consider the following table structures related to a university for the below questions.
EMPLOYEE
NAME
VARCHAR(30)
NOT NULL
EID
VARCHAR(10)
NOT NULL
DEPTNO
INT(5)
NOT NULL
HODEID
VARCHAR(10)
SALARY
INT(10)
PRIMARY KEY (EID),
FOREIGN KEY (HODEID) REFERENCES EMPLOYEE (EID),
FOREIGN KEY (DEPTNO) REFERENCES DEPARTMENT (DID);
DEPARTMENT
DID
INT(5)
NOT NULL
DNAME
VARCHAR(30)
NOT NULL
HODID
VARCHAR(10)
NOT NULL
HODNAME
VARCHAR(30)
PRIMARY KEY (DID),
UNIQUE (DNAME),
FOREIGN KEY (HODID) REFERENCES EMPLOYEE (EID);
PROJECT WORK
EMPID
VARCHAR(10)
NOT NULL
PROJNO
INT(5)
NOT NULL
PROJECTLOC
VARCHAR(30)
NOT NULL
PRIMARY KEY (EMPID, PROJNO),
FOREIGN KEY (EMPID) REFERENCES EMPLOYEE (EID);
Refer table structures given above. The university decided to give all employees in the 'SCIENCE' department a $20\%$ rise in salary. Which of the following query or queries will compute the above results?
(A)
UPDATE EMPLOYEE
SET SALARY = SALARY * 1.20
WHERE DEPTNO IN (SELECT DID FROM DEPARTMENT WHERE DNAME='SCIENCE');
(B)
UPDATE TABLE EMPLOYEE
SET SALARY = SALARY * 1.20
WHERE DNAME='SCIENCE';
(C)
ALTER TABLE EMPLOYEE
SET SALARY = SALARY * 1.20
WHERE DEPTNO IN (SELECT DNAME FROM DEPARTMENT WHERE DNAME='SCIENCE');
Choose the correct answer from the options given below:
1
(A) and (B) only 2
(A) only 3
(B) and (C) only 4
(C) only Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution We need to increase the salary of all employees who belong to the 'SCIENCE' department. The salary is stored in EMPLOYEE table. The department name is stored in DEPARTMENT table. So, first we need to find the DID of the 'SCIENCE' department. This can be done by: SELECT DID FROM DEPARTMENT WHERE DNAME='SCIENCE' Then update salary of employees whose DEPTNO matches that DID. So, correct query is: UPDATE EMPLOYEE SET SALARY = SALARY * 1.20 WHERE DEPTNO IN (SELECT DID FROM DEPARTMENT WHERE DNAME='SCIENCE'); Therefore, query (A) is correct. Query (B) is incorrect because UPDATE TABLE is not valid syntax. Also, DNAME is not present in EMPLOYEE table. Query (C) is incorrect because ALTER TABLE is used to change table structure, not to update data. Also, it compares DEPTNO with DNAME, which is wrong. Therefore, only query (A) is correct.
Qus : 68
UGC NET Computer Science PYQ 2020
3
The number of positive integers not exceeding $100$ that are either odd or the square of an integer is _____
1
63 2
59 3
55 4
50 Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Positive odd integers not exceeding $100$ are: $1,3,5,\ldots,99$ Number of odd integers $=50$ Perfect squares not exceeding $100$ are: $1^2,2^2,3^2,\ldots,10^2$ Number of perfect squares $=10$ Odd perfect squares are: $1^2,3^2,5^2,7^2,9^2$ Number of odd perfect squares $=5$ Required number: $50+10-5=55$
Qus : 70
UGC NET Computer Science PYQ 2020
4
Which of the following pairs of propositions are not logically equivalent?
1
$((p\to r)\land(q\to r))$ and $((p\lor q)\to r)$ 2
$p\leftrightarrow q$ and $(\neg p\leftrightarrow \neg q)$ 3
$((p\land q)\lor(\neg p\land \neg q))$ and $p\leftrightarrow q$ 4
$((p\land q)\to r)$ and $((p\to r)\land(q\to r))$ Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Check option (a): $(p\to r)\land(q\to r)$ $=(\neg p\lor r)\land(\neg q\lor r)$ $=(\neg p\land\neg q)\lor r$ $=\neg(p\lor q)\lor r$ $=(p\lor q)\to r$ So, option (a) is logically equivalent. Option (b) is also equivalent because if $p$ and $q$ have same truth value, then $\neg p$ and $\neg q$ also have same truth value. Option (c) is the standard form of biconditional: $p\leftrightarrow q\equiv(p\land q)\lor(\neg p\land\neg q)$ So, option (c) is logically equivalent. Now check option (d): $((p\land q)\to r)=\neg(p\land q)\lor r=\neg p\lor\neg q\lor r$ But, $(p\to r)\land(q\to r)=(\neg p\lor r)\land(\neg q\lor r)$ Both are not always same.
Qus : 72
UGC NET Computer Science PYQ 2020
1
Consider a machine with a byte addressable main memory of $2^{16}$ bytes and block size of $8$ bytes. Assume that a direct mapped cache consisting of $32$ lines used with this machine. How many bits will be there in Tag, line and word field of format of main memory addresses?
1
$8,5,3$ 2
$8,6,2$ 3
$7,5,4$ 4
$7,6,3$ Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Main memory size $=2^{16}$ bytes So, address size $=16$ bits. Block size $=8$ bytes $=2^3$ bytes So, word field bits $=3$ Cache has $32$ lines $=2^5$ lines So, line field bits $=5$ Now, Tag bits $=16-5-3=8$ Therefore, Tag, line and word bits are: $8,5,3$
Qus : 73
UGC NET Computer Science PYQ 2020
4
The following program is stored in memory unit of the basic computer. What is the content of the accumulator after the execution of program? All location numbers listed below are in hexadecimal.
Location Instruction 210 CLA 211 ADD 217 212 INC 213 STA 217 214 LDA 218 215 CMA 216 AND 217 217 1234H 218 9CE2H
1
$1002H$ 2
$2011H$ 3
$2022H$ 4
$0215H$ Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Initially, $AC=0000H$ After $CLA$: $AC=0000H$ After $ADD\ 217$: $AC=0000H+1234H=1234H$ After $INC$: $AC=1235H$ After $STA\ 217$: $M[217]=1235H$ After $LDA\ 218$: $AC=9CE2H$ After $CMA$: $AC=\overline{9CE2H}=631DH$ Now execute $AND\ 217$: $AC=631DH\ AND\ 1235H$ $631DH=0110\ 0011\ 0001\ 1101$ $1235H=0001\ 0010\ 0011\ 0101$ So, $AC=0000\ 0010\ 0001\ 0101=0215H$
Qus : 78
UGC NET Computer Science PYQ 2020
3
Suppose you are compiling on a machine with $1$-byte chars, $2$-byte shorts, $4$-byte ints, and $8$-byte doubles, and with alignment rules that require the address of every primitive data element to be an integer multiple of the element's size. Suppose further that the compiler is not permitted to reorder fields; padding is used to ensure alignment. How much space will be consumed by the following array? struct { short s; char c; short t; char d; double r; int i; } A[10];
1
$150$ bytes 2
$320$ bytes 3
$240$ bytes 4
$200$ bytes Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution $short\ s$: starts at offset $0$, size $2$, next offset $2$ $char\ c$: starts at offset $2$, size $1$, next offset $3$ $short\ t$: needs multiple of $2$, so $1$ byte padding, starts at offset $4$, next offset $6$ $char\ d$: starts at offset $6$, size $1$, next offset $7$ $double\ r$: needs multiple of $8$, so $1$ byte padding, starts at offset $8$, next offset $16$ $int\ i$: needs multiple of $4$, starts at offset $16$, next offset $20$ Struct size must be multiple of maximum alignment $8$. So, $20$ is padded to $24$ bytes. For $A[10]$: $10\times24=240$ bytes
Qus : 79
UGC NET Computer Science PYQ 2020
1
Consider the following recursive Java function $f$ that takes two long arguments and returns a float value: public static float f(long m, long n) { float result = (float)m / (float)n; if (m < 0 || n < 0) return 0.0f; else result -= f(m * 2, n * 3); return result; } Which of the following real values best approximates the value of $f(1,3)$?
1
0.2 2
0.4 3
0.6 4
0.8 Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution $f(1,3)=\frac{1}{3}-f(2,9)$ $=\frac{1}{3}-\frac{2}{9}+\frac{4}{27}-\frac{8}{81}+\cdots$ This is a geometric series with first term $\frac{1}{3}$ and common ratio $-\frac{2}{3}$. Sum: $\frac{\frac{1}{3}}{1-(-\frac{2}{3})}=\frac{\frac{1}{3}}{\frac{5}{3}}=\frac{1}{5}=0.2$
Qus : 81
UGC NET Computer Science PYQ 2020
4
Consider a relational schema $S=(U,V,W,X,Y,Z)$ on which the following functional dependencies hold: $\{U\to V,\ VW\to X,\ Y\to W,\ X\to U\}$ Which are the candidate keys among following options?
1
UY, VY 2
UY, VY, XY 3
UYZ, VYZ, VWZ 4
UYZ, VYZ, XYZ Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Attributes $Y$ and $Z$ are not present on RHS of any FD. So, every candidate key must contain $Y$ and $Z$. Now check: $(UYZ)^+=\{U,Y,Z,V,W,X\}$, so $UYZ$ is a key. $(VYZ)^+=\{V,Y,Z,W,X,U\}$, so $VYZ$ is a key. $(XYZ)^+=\{X,Y,Z,U,V,W\}$, so $XYZ$ is a key. Thus, candidate keys are: $UYZ,\ VYZ,\ XYZ$
Qus : 82
UGC NET Computer Science PYQ 2020
4
Consider a hypothetical machine with $3$ pages of physical memory, $5$ pages of virtual memory, and $\langle A,B,C,D,A,B,E,A,B,C,D,E,B,A,B\rangle$ as the stream of page references by an application. If $P$ and $Q$ are the number of page faults with FIFO and LRU page replacement algorithms respectively, then $(P,Q)=$ _____.
1
(11,10) 2
(12,11) 3
(10,11) 4
(11.12) Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution There are $3$ page frames. For FIFO page replacement, page faults are: $P=11$ For LRU page replacement, page faults are: $Q=12$ So, $(P,Q)=(11,12)$
Qus : 83
UGC NET Computer Science PYQ 2020
3
Consider a disk system having $60$ cylinders. Disk requests are received for cylinders $10,22,20,2,40,6,38$ in that order. Assuming the disk head is currently at cylinder $20$, what is the time taken to satisfy all the requests if it takes $2$ milliseconds to move from one cylinder to adjacent one and SSTF algorithm is used?
1
$240$ milliseconds 2
$96$ milliseconds 3
$120$ milliseconds 4
$112$ milliseconds Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Using SSTF, from cylinder $20$ the order is approximately: $20\to20\to22\to10\to6\to2\to38\to40$ Total head movement: $0+2+12+4+4+36+2=60$ cylinders Time for one cylinder movement $=2$ ms Total time: $60\times2=120$ milliseconds
Qus : 84
UGC NET Computer Science PYQ 2020
2
Suppose you have a Linux file system where the block size is $2K$ bytes, a disk address is $32$ bits, and an i-node contains the disk addresses of the first $12$ direct blocks of file, a single indirect block, and a double indirect block. Approximately, what is the largest file that can be represented by an i-node?
1
$513$ Kbytes 2
$513$ MBytes 3
$537$ Mbytes 4
$537$ KBytes Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Block size $=2K=2048$ bytes Disk address size $=32$ bits $=4$ bytes Number of addresses in one block: $\frac{2048}{4}=512$ Direct blocks $=12$ Single indirect blocks $=512$ Double indirect blocks: $512\times512=262144$ Total data blocks: $12+512+262144=262668$ Total file size: $262668\times2048=537944064$ bytes In MB: $\frac{537944064}{1024\times1024}\approx513$ MB
Qus : 88
UGC NET Computer Science PYQ 2020
3
A company has a choice of two languages $L_1$ and $L_2$ to develop a software for their client. Number of LOC required to develop an application in $L_2$ is thrice the LOC in language $L_1$. Also, software has to be maintained for next $10$ years. Various parameters for two languages are given below to decide which language should be preferred for development.
PARAMETER $L_1$ $L_2$ Man-year needed for development LOC/1000 LOC/1000 Development cost Rs. 70,000 Rs. 90,000 Cost of Maintenance per year Rs. 1,00,000 Rs. 40,000
Total cost of project includes cost of development and maintenance. What is the LOC for $L_1$ for which cost of developing the software with both languages must be same?
1
2000 2
6000 3
3000 4
5000 Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Let LOC for $L_1=x$ Then LOC for $L_2=3x$ For $L_1$: Development cost $=\frac{x}{1000}\times70000=70x$ Maintenance cost for $10$ years: $10\times100000=1000000$ Total cost for $L_1$: $70x+1000000$ For $L_2$: Development cost $=\frac{3x}{1000}\times90000=270x$ Maintenance cost for $10$ years: $10\times40000=400000$ Total cost for $L_2$: $270x+400000$ Now both costs are same: $70x+1000000=270x+400000$ $600000=200x$ $x=3000$
Qus : 89
UGC NET Computer Science PYQ 2020
2
A Software project was estimated at 864 Function Points. A six person team will be assigned to project consisting of a requirement gathering person, one designer, two programmers and two testers. The salary of the designer is ₹70,000 per month, requirement gatherer is ₹50,000 per month, programmer is ₹60,000 per month and a tester is ₹60,000 per month. Average productivity for the team is 12 FP per person month. Which of the following represents the projected cost of the project?
1
₹33,20,000 2
₹43,20,000 3
₹33,10,000 4
₹22,10,000 Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution Total effort required: $Effort=\frac{864}{12}=72$ person-months Team size $=6$ Project duration: $\frac{72}{6}=12$ months Monthly team cost: $50000+70000+2(60000)+2(60000)$ $=50000+70000+120000+120000=360000$ Total project cost: $360000\times12=4320000$ So, projected cost is ₹43,20,000.
Qus : 94
UGC NET Computer Science PYQ 2020
3
Consider $L=L_1\cap L_2$ where $L_1=\{0^m1^m20^n1^n\mid m,n\ge 0\}$ $L_2=\{0^m1^n2^k\mid m,n,k\ge 0\}$ Then, the language $L$ is
1
Recursively enumerable but not context free 2
Regular 3
Context free but not regular 4
Not recursive Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution In $L_1$, after symbol $2$, we have $0^n1^n$. But in $L_2$, after symbol $2$, no $0$ or $1$ can appear. So, for intersection, $n=0$ in $L_1$. Thus, $L=\{0^m1^m2\mid m\ge0\}$ This language is context free but not regular.
Qus : 99
UGC NET Computer Science PYQ 2020
3
Using RSA public key cryptosystem, if $p=3,\ q=11$ and $d=7$, find the value of $e$ and encrypt the number $19$.
1
$20,19$ 2
$33,11$ 3
$3,28$ 4
$77,28$ Go to Discussion
UGC NET Computer Science UGC NET PYQ
UGC NET Computer Science UGC NET Computer Science Nov 2020 (Paper II) PYQ
Solution $n=pq=3\times11=33$ $\phi(n)=(p-1)(q-1)=2\times10=20$ Now, $d\times e\equiv1\pmod{\phi(n)}$ $7e\equiv1\pmod{20}$ $e=3$, because $7\times3=21\equiv1\pmod{20}$ Now encrypt $M=19$: $C=M^e\mod n$ $C=19^3\mod33$ $19^2=361\equiv31\pmod{33}$ $19^3=31\times19=589\equiv28\pmod{33}$ So, $e=3$ and encrypted value $=28$.
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