Recent questions in Discrete Mathematics

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1

UGC NET jUNE 2006 -QN 5
Let A = {x | -1<x<1} = B. The function f(x)=x/2 from A to B is: (A) injective (B) surjective (C) both injective and surjective (D) neither injective nor surjective How it can be both injective and surjective ??

asked 6 hours ago in Mathematical Logic by Aparna Deepak (43 points) | 12 views

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2

graph theory
"A planar graph need not to be connected" Can someone plz explain with an example .

asked 16 hours ago in Set Theory & Algebra by Pawan Kumar 2 Junior (557 points) | 16 views

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1 answer

3

permutation and combination
A roller coaster has five cars, each containing four seats, two in front and two in back. There are 20 people ready for a ride. In how many ways can the ride begin? What if a certa:in two people want to sit in different cars?

asked 22 hours ago in Mathematical Logic by arch Junior (905 points) | 14 views

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1 answer

4

permutation and combination
A footrace takes place among four runners. If ties are allowed (even all four runners finishing at the same time), how many ways are there for the race to finish?

asked 22 hours ago in Mathematical Logic by arch Junior (905 points) | 12 views

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1 answer

5

permutation and combination
How many sets of three integers between 1 and 20 are possible if no two consecutive integers are to be in a set?

asked 23 hours ago in Mathematical Logic by arch Junior (905 points) | 23 views

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1 answer

6

Problem in sets
more than 1 can be true or false

asked 2 days ago in Set Theory & Algebra by Vicky rix Loyal (3.7k points) | 31 views

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7

Maths: functions: is given function bijective?

asked 2 days ago in Set Theory & Algebra by manu00x Veteran (11.1k points) | 43 views

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8

Mathematics Gate 2008

asked 3 days ago in Mathematical Logic by air1ankit Junior (841 points) | 12 views

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1 answer

9

Self doubt - Power Set
Can you conclude A = B if A and B are 2 sets with the same power set ? Doubt : Is power set of a set unique ?

asked 3 days ago in Set Theory & Algebra by just_bhavana Loyal (4.8k points) | 28 views

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1 answer

10

Function Composition
For gof to be one-to-one, f must be one-to-one but reverse is not true. Is the above statement correct? According to me both f and g must be one-to-one for gof to be one-to-one. I took below examples: (i) f is one-to-one and g ... f(1)) and g(f(2)) both gives α which implies that gof is one-to-one. Are above examples correct? If yes, please explain.

asked 3 days ago in Set Theory & Algebra by aishwarydewangan (235 points) | 11 views

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11

GATE-CS-2014-(Set-1)
Which one of the following propositional logic formulas is TRUE when exactly two of p, q, and r are TRUE? Can anyone please share solution for this without using truth tables?

asked 3 days ago in Mathematical Logic by preps (17 points) | 20 views

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12

Propositional and First Order Logic GATE-CS-2006

asked 3 days ago in Mathematical Logic by preps (17 points) | 46 views

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13

PERMUTATIONS

asked 3 days ago in Combinatory by Parshu gate (381 points) | 27 views

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2 answers

14

limits doubt
llimit 1 / ( 1 + (sin x / x ) ) // can we directly put sin x / x =1 is this valid because its not in product form ? x ->0

asked 3 days ago in Mathematical Logic by sumit goyal 1 Loyal (2.5k points) | 23 views

0 votes

1 answer

15

doubt
Suppose that we draw a card from a deck of 52 cards and replace it before the next draw. In how many ways can 10 cards be drawn so that the tenth card is a repetition of a previous draw.

asked 4 days ago in Combinatory by Divyanshu Tiwari (15 points) | 9 views

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1 answer

16

UGCNET-dec2009-ii-22
The number of edges in a complete graph of n vertices is (A) n (B) n(n – 1)/2 (C) n(n + 1)/2 (D) (n^2)/2

asked 4 days ago in Graph Theory by rishu_darkshadow Active (2k points) | 18 views

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1 answer

17

[Discrete maths] Spanning trees

asked 4 days ago in Graph Theory by rahul sharma 5 Veteran (11.2k points) | 35 views

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18

UGCNET-dec2009-ii-04
P : “Program is a step by step execution of the instructions”. Given P, which of the following is true ? (A) Program is a subset of an instruction set. (B) Program is a sequence of a subset of an instruction set. (C) Program is a partially ordered set of an instruction set. (D) All of the above

asked 4 days ago in Mathematical Logic by rishu_darkshadow Active (2k points) | 9 views

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2 answers

19

UGCNET-dec2009-ii-02
Circle has ____________ (A) No vertices (B) Only 1 vertex (C) ∞ vertices (D) None of these

asked 4 days ago in Graph Theory by rishu_darkshadow Active (2k points) | 21 views

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20

UGCNET-Dec2009-ii-01
If she is my friend and you are her friend, then we are friends. Given this, the friend relationship in this context is ____________. (i) commutative (ii) transitive (iii) implicative (iv) equivalence (A) (i) and (ii) (B) (iii) (C) (i), (ii), (iii) and (iv) (D) None of these

asked 4 days ago in Set Theory & Algebra by rishu_darkshadow Active (2k points) | 8 views

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21

instrunmentation and measurements [closed]

asked 4 days ago in Mathematical Logic by Hassan Javaid 3 (23 points) | 10 views

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22

instrunmentation and measurements [closed]

asked 4 days ago in Mathematical Logic by Hassan Javaid 3 (23 points) | 8 views

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23

instrunmentation and measurements [closed]

asked 4 days ago in Mathematical Logic by Hassan Javaid 3 (23 points) | 8 views

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1 answer

24

Function
How many onto function are there from a set with 5 element to a set with 4 elements? A. 340 B. 240 C. 440 D. 540

asked 4 days ago in Set Theory & Algebra by mystylecse Active (1.6k points) | 23 views

0 votes

1 answer

25

combinatorics
10 persons are seated at round table. The number of ways of selecting 3 persons out of them if no two persons are adjacent to each other is?

asked 5 days ago in Combinatory by Kaluti Active (2.3k points) | 18 views

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26

Sub-groups
Find all subgroups of a cyclic group of order 12. Also what is the number of generators? Doubt: I got subgroups as a, a2, a3, a4, a6 and a12. How to identify the identity element among these?

asked 6 days ago in Mathematical Logic by just_bhavana Loyal (4.8k points) | 28 views

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1 answer

27

graph - self doubt
Graph G has atleast 1 edge then which are true a) G has a hamiltonian circuit b) Every cycle of G is of even length

asked 6 days ago in Graph Theory by A_i_$_h Loyal (4.6k points) | 31 views

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1 answer

28

graph
Assume undirected graph G is connected . G has 6 vertices and 10 edges. Find the minimum number of edges whose deletion from graph G is always guaranteee that it will become disconnected

asked 6 days ago in Graph Theory by A_i_$_h Loyal (4.6k points) | 34 views

+1 vote

1 answer

29

number of strings
COnsider a string of lngth 10 containing only 0 and 1 the number of strings containg exactly 3 0's or 3 1's is ____________

asked 6 days ago in Set Theory & Algebra by A_i_$_h Loyal (4.6k points) | 33 views

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30

relations
a relation is defined as (a , b) R ( c , d) iff a=c or b=d is R antisymmetric ?

asked 6 days ago in Set Theory & Algebra by A_i_$_h Loyal (4.6k points) | 22 views

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