Discrete mathematics Definition and 106 Threads

Discrete mathematics is the study of mathematical structures that are fundamentally discrete rather than continuous. In contrast to real numbers that have the property of varying "smoothly", the objects studied in discrete mathematics – such as integers, graphs, and statements in logic – do not vary smoothly in this way, but have distinct, separated values. Discrete mathematics therefore excludes topics in "continuous mathematics" such as calculus or Euclidean geometry. Discrete objects can often be enumerated by integers. More formally, discrete mathematics has been characterized as the branch of mathematics dealing with countable sets (finite sets or sets with the same cardinality as the natural numbers). However, there is no exact definition of the term "discrete mathematics." Indeed, discrete mathematics is described less by what is included than by what is excluded: continuously varying quantities and related notions.
The set of objects studied in discrete mathematics can be finite or infinite. The term finite mathematics is sometimes applied to parts of the field of discrete mathematics that deals with finite sets, particularly those areas relevant to business.
Research in discrete mathematics increased in the latter half of the twentieth century partly due to the development of digital computers which operate in discrete steps and store data in discrete bits. Concepts and notations from discrete mathematics are useful in studying and describing objects and problems in branches of computer science, such as computer algorithms, programming languages, cryptography, automated theorem proving, and software development. Conversely, computer implementations are significant in applying ideas from discrete mathematics to real-world problems, such as in operations research.
Although the main objects of study in discrete mathematics are discrete objects, analytic methods from continuous mathematics are often employed as well.
In university curricula, "Discrete Mathematics" appeared in the 1980s, initially as a computer science support course; its contents were somewhat haphazard at the time. The curriculum has thereafter developed in conjunction with efforts by ACM and MAA into a course that is basically intended to develop mathematical maturity in first-year students; therefore, it is nowadays a prerequisite for mathematics majors in some universities as well. Some high-school-level discrete mathematics textbooks have appeared as well. At this level, discrete mathematics is sometimes seen as a preparatory course, not unlike precalculus in this respect.The Fulkerson Prize is awarded for outstanding papers in discrete mathematics.

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  1. J

    Discrete Mathematics - Void Sets being Subsets of other Void Sets

    Homework Statement Hello. Here is the question: Determine whether or not R is some sort of order relation on the given set X. X = {∅, {∅}, {{∅}} } and R ε ⊆. I can't seem to figure out why the ordered pairs given are what they are. Homework Equations None. The Attempt at...
  2. S

    Discrete Mathematics : Functions and Relations : Question 2c

    Homework Statement c) Is 'g' a surjective function (onto) ? Justify your answer. Homework Equations Let 'f' be a relation on ℤ (the set of integers) , defined by the entrance requirement : (x;y) ∊ ƒ iff y = x + 15 and let 'g' be the function on ℤ defined by the...
  3. J

    Discrete Mathematics - Operations with sets

    I apologize for the repost, but I had no replies to my previous post. I figured that I didn't put down a good enough attempt of a solution. I will try to explain what I did in more detail. I have read the rules for the forum, but if I'm still doing something wrong, please tell me. I want to...
  4. S

    Discrete Mathematics : Functions and Relations : Question 2

    Homework Statement Determine the dom(g) Homework Equations Let 'f' be a relation on ℤ (the set of integers) , defined by the entrance requirement : (x;y) ∊ ƒ iff y = x + 15 and let 'g' be the function on ℤ defined by the entrance requirement : (x;y)...
  5. S

    Discrete Mathematics : Proof : Question 1

    Homework Statement Question 1 : a) Use Venn diagrams to determine whether or not, for all subnets A,B and C of a universal set U, (A-B) ∪ C = (A∪C) - (A∩B) b) If the statement appears to hold, give a proof, if not, give a counter example. Homework Equations (A-B) ∪...
  6. S

    Discrete Mathematics - Basic Set Theory : Assignment review : Q2

    Question 2: -------------------- Homework Statement Consider the following sets, where U represents a universal set : U = {1, 2, 3, 4, ∅, {1}} A = {1, 3} B = {{1}, 1} C = {2 , 4} D = { ∅ , 1, 2 } Homework Equations A+D is the set : (Choose only one ) 1. {1, 3}...
  7. S

    Discrete Mathematics - Basic Set Theory : Assignment review : Q1

    Question 1 : -------------------- Homework Statement Consider the following sets, where U represents a universal set : U = {1, 2, 3, 4, ∅, {1}} A = {1, 3} B = {{1}, 1} C = {2 , 4} D = { ∅ , 1, 2 } Homework Equations Choose the correct option : D - B is the set ...
  8. S

    Set Theory : Discrete Mathematics

    Homework Statement The Question data is as follows : Consider the following sets, where U represents a universal set : U = {1, 2, 3, 4, ∅, {1}} A = {1, 3} B = {{1}, 1} C = {2 , 4} D = { ∅ , 1, 2 ) Homework Equations Which one of the following statements is true ? 1. The...
  9. 7

    Ph.D. programs with discrete mathematics

    I've been having trouble finding many pure math Ph.D. programs with active research groups in the general field of discrete mathematics (perhaps due to its interdisciplinary nature). I'm only aware of the top schools in this field (e.g. Carnegie Mellon, Georgia Tech, UCSD, Rutgers); can anyone...
  10. N

    Need help in solving 2 questions of Discrete Mathematics

    Q 1. On a circular island we build n straight dams going from Sea to sea, so the ever two intersect but no three go through the same point. Use Euler’s Formula to determine how many Q 2. Into how many parts do two quadrilaterals divide the plane, If (a) They are convex (b) They are not...
  11. V

    Discrete Mathematics : Counting and Probability

    Homework Statement Question 1: a) Suppose you have brought four pens of different colours to the exam. For each of the ten question on the exam, you choose one pen. In how many ways can this be done? b) In how many ways can you distribute six bananas and five oranges between three children...
  12. S

    Discrete Mathematics: Proof problem for even integer

    Homework Statement For every non-negative integer z, z2 - 3z is an even integer. Prove this statement. So far, I have learned about direct proofs and indirect proofs such as contraposition and contradiction. Homework Equations An integer z is odd when there is an integer a so that z = 2a+1...
  13. M

    Having Trouble Adapting Discrete Mathematics

    Ok, so I'm having difficulty adapting to subjects like set theory etc. For example this question: L.{A,a} = {A, a, b, ab, ba, aba} Find L Now, I know the answer but it was a battle getting there. It took me 30 mins before giving up and turning on my PC. I got annoyed so much that...
  14. H

    Courses What courses is Discrete Mathematics necessary for? I may need to push it back.

    None of my advanced courses require discrete math as a requisite. In fact, the only course that does explicitly require it is not on my degree plan of operations research. However, is this going to bother me when it comes time for say Real Analysis, Advanced Calc, or Abstract Algebra? I think...
  15. K

    How many ways can we turn off 5 lamps along a street?

    Homework Statement There are 17 street lamps along a straight street. In order to save electricity and not affect the regular use at the same time, we can shut down 5 of these lamps. But we cannot turn off a lamp at either end of the street, and we cannot turn off a lamp adjacent to a lamp...
  16. K

    Combinatorics of Street Lamp Arrangements

    Homework Statement There are 17 street lamps along a straight street. In order to save electricity and not affect the regular use at the same time, we can shut down 5 of these lamps. But we cannot turn off a lamp at either end of the street, and we cannot turn off a lamp adjacent to a lamp...
  17. T

    Discrete Math: Symmetric Closure & Numerical Analysis

    Discrete Mathematics -- Symmetric Closure Math help in Numerical Analysis, Systems of I can't seem to find the way to approach this problem. Because it has symbols I don't know how to type here, I have attached an image here instead. Please help me if you can. Any input would be greatly...
  18. B

    Discrete Math: Learn About Linear Algebra & Analytic Geometry

    Hi, i have studied discrete math and there are topics like linear algebra and analytic geometry and googling i found that there are not in other courses, what are the topics in your discrete math courses?
  19. N

    Discrete Mathematics - (A∪B)-(A∩B)=(A-B)∪(B-A) - prove by cases?

    Discrete Mathematics - (A∪B)-(A∩B)=(A-B)∪(B-A) - prove by cases?? Hi, I'm new to these forums so please redirect me if I've posted this in the wrong place. I'm trying to graduate and this is my last class, but as I'm not a math major, I'm really struggling with this particular problem. I've...
  20. B

    Taking Discrete Mathematics in August (Help)

    Hi all, I am going to be taking Discrete Mathematics in August and my last Math course was about 5 years ago. I am a little intimidated to just 'jump' back into Math especially a course like this one. Can anyone who was successful give me a few pointers? I ordered the Textbook and will...
  21. B

    Solving Discrete Math: Integer & Algorithm Homework

    Hi guys! I got really stuck with a Discrete Mathematics homework in Integers and Algorithms. I know it is not very clear due to lack of symbols. If anyone didn't understand some part of the exercise I would like to clarify it. The exercise is the following : Homework Statement Define for B...
  22. Y

    Prove Pascal's Triangle-type Function - Discrete Mathematics

    Homework Statement For all n ∈ Z+, the function Pn of i variables is defined recursively as follows: Pn(x1,...,xn) = Pn-1(x1 + x2, x2 + x3,...,xn-1 + xn) and P1(x1) = x1. Find a closed formula for Pn. Homework Equations Pn(x1,...,xn) = Pn-1(x1 + x2, x2 + x3,...,xn-1 + xn) and P1(x1)...
  23. R

    AI search strategies using discrete mathematics

    Homework Statement The question is to provide a new composite heuristic h3 that is admissible and dominates h1 and h2. Then show the cost of each of the states through H according to h3. Homework Equations States: A B C D E F G H h1: 10,12,12,6,7,7,2,10 h2: 8, 9, 14,4,9,7,1,9...
  24. M

    What is mathematical analysis and/or discrete mathematics used for?

    I am starting a maths major and I will going to go into pure maths. I am going to specialize in either analysis or discrete maths. I understand that mathematical analysis has a very strong connection to calculus and that discrete mathematics is used mainly in the cryptography and security...
  25. A

    2.2 Set Operations: Discrete Mathematics and its application

    Ex 36, p 147. Let f be a function from the set A to the Set B. Let S and T be the subset of A. Show that b) f(S \cap T) \subseteq f(S) \cap f(T). Thanks.
  26. T

    Discrete Mathematics Proof Problem

    Homework Statement Which is larger, square root of 2 or cubed root of 3? Prove one is larger than the other without using decimal approximations for either number. The Attempt at a Solution I attempted to solve this through the contradiction that they were even. If they are not even then...
  27. B

    What's the best discrete mathematics textbook?

    Apparently everyone uses either Discrete Mathematics and Its Applications by Kenneth H. Rosen or Discrete Mathematics with Applications by Susanna S. Epp. Are these really the best ones? Both are very long texts which make me think they're not rigorous and they're descriptive like Stewart’s...
  28. G

    Discrete mathematics and its application 2.4 problem 26

    Homework Statement Find a formula for when m \sum k=0 the flooring function of[k1/3 ] ,m is a positive integer. Homework Equations n\prod j=m aj The Attempt at a Solution the flooring function of[k1/3] = K the summation of K is \frac{m(m+1)}{2} There's a table of...
  29. C

    Discrete Mathematics theory problem

    Homework Statement I'm supposed to prove the following. I assume it means that (w,v) and (v,w) don't both belong to f. If they do, then f certainly isn't a single function. For instance take f= x^2. The point (2,4) certainly belongs to f, but the point (4,2) does not. It in fact belongs to...
  30. T

    Stuck on Proofs in Discrete Mathematics?

    Hello all, I am stuck on some homework, basically I am stuck on the problems dealing with proofs. I am not asking for complete answers just any direction would be helpful. 1) I have to prove the Grötzsch graph is not 3-colorable (vertex can be colored in such a way that no edge shares 2...
  31. E

    Discrete Mathematics Book Recommendation

    Hello, I'm looking for a decent Discrete Mathematics book.. Well, - Discrete Mathematics & Its Applications. - Discrete Mathematics With Its Applications. Are the top-sellers and the top-rated books @ Amazon on this field. Has anyone read any of them? Recommendations? Pros & Cons? I'm...
  32. F

    Discrete mathematics (PMI, composition, onto)

    Homework Statement a.) F = {(1, a), (2, b), (3, a), (4, c)} G = {(b, 1), (a, 2), (c, 3)} i. Find F o G ii. Find G o F b.) A function F: N x N --> N is represented 2(m + n) + 1 for F(m, n) i. Is F one-to-one? ii. Is F onto? c.) Prove by Mathematical Induction...
  33. F

    Discrete mathematics induction

    Homework Statement Prove that for all integers a >= 1, a^n - 1 is divisible by a - 1 for all n >= 1. Homework Equations None. The Attempt at a Solution Proof - Let P(n): a^n - 1 is divisible by a - 1, then P(1): a^1 - 1 is divisible by a - 1 is TRUE since a^1 - 1 = a - 1, and...
  34. M

    3.1 Algorithms (Discrete Mathematics)

    Describe an algorithm that takes as input a list of n distinct integers and finds the location of the largest even integer in the list or returns 0 if there are no even integers in the list. Please Help me on how to solve this type of question I am clueless.
  35. G

    Discrete mathematics: incursion

    Homework Statement a 1= 2, a k+1, 2ak-1 Homework Equations What is the 5th term The Attempt at a Solution a1= 2 a2=2(2)-1= 3 a3=2(3)-1=5 a4=2(4)-1=7 a5=2(5)-1=9 5th term =9?
  36. M

    Can You Prove This Theorem Using Discrete Mathematics Tables?

    :confused: Construct a formal proof of the theorem: If (p-> q), (neg [r] -> s), and (neg [q] V neg [s], then (p-> r). [refer to table of logical equivalences (p62) and the table of logical implication (p62)]The tables are in the textbook Kenneth Ross, 5th edition, Discrete Math's...
  37. M

    Logics and Proof - Discrete Mathematics

    Prove or disapprove that the product of two rational numbers is irrational How do you solve this? Thanks
  38. M

    2.2 Set Operations: Discrete Mathematics and its application

    page.130 Ex.20 Ex.20 Show that if A and B are sets, then (A\capB) \bigcup (A\capB) = A. how do u solve this? The Attempt at a Solution
  39. M

    Solve Discrete Math Problem: f(x,y)= 4x+y-4

    I know I have to write an equation to solve the problem down. But I really don't know how to use the given information. I did it by enumeration, but I don't get it how this will be shown by an algebriac argument. Please some one help me at least with an idea. If S = {1,2,3,4}, consider the...
  40. S

    Discrete Mathematics (confused and help wanted)

    Dear all, I have an example taken from the book titled "Discrete Mathematics For Computer Science" by Kenneth Bogart. In the book, page 11, example 1.2-2, it says: Write down all the functions from the two element set {1,2} to the two element set {a,b}. I couldn't understand the...
  41. T

    Where can I find a comprehensive resource for learning discrete mathematics?

    Hi, Im after some advice on what materials to use in order to gain a fairly 'decent' understanding of the following topics: Elementary Set Theory, Subsets, Unions, Intersections, Complements. Logic, Functions, Mappings, Injectivity. Subjectivity. Bijectivity, Permutations, Proof techniques...
  42. G

    What is the range of the function g: ZxZ --> ZxZ given by g(m,n)=(m-n,m+n)?

    Homework Statement Find the range of the function g: ZxZ --> ZxZ given by g(m,n)=(m-n,m+n). Hints: First recall that if f: A ---> B then Range (f)={b e B such that there exists an A in A with b=f(a). Second, if you claim that some set C is the range, then you must show that i) C is a subset...
  43. A

    Discrete Mathematics - Combinations/Factorials?

    Homework Statement An electronic switch bank consists of a row of six on - off switches. How many different settings are possible if exactly three of the switches are set to off? (a) 12 (b) 144 (c) 60 (d) 30 (e) 20 Homework Equations Factorial rule...
  44. A

    Discrete Mathematics - Permutations/Combinations?

    Homework Statement A certain state issues a series of automobile license plates such that each license plate must have 2 letters followed by three digits. An example license plate would be AD 025 . If the letters and the digits cannot be repeated, how many different license plates can be...
  45. F

    Propositional logic Discrete Mathematics

    [SOLVED] Propositional logic Discrete Mathematics Homework Statement Assuming atleast one of the following statements is true, which one is it? why? a. Exactly one of these statements is true b. Exactly two of these statements are true c. Exactly three of these statements are true d...
  46. T

    Discrete Mathematics with possible Quotient Remainder Theorem

    Homework Statement For all integers m, m^{}2=5k, or m^{}2=5k+1, or m^{}2=5k+4 for some integer k. Relevant equations I'm pretty sure we have to use the Quotient Remainder THM, which is: Given any integer n and positive integer d, there exists unique integers q and r such that...
  47. T

    Discrete Mathematics Absolute Value Proof

    Homework Statement Prove the following statement: For all real numbers x and y, |x| times |y| = |xy| Homework Equations I really don't know how to start this as a formal proof. The Attempt at a Solution I was thinking I'd have to break it down into four cases and logically prove...
  48. T

    Discrete Mathematics: Solving for x in a System of Equations

    Homework Statement Suppose a, b, and c are integers and x, y, and z are nonzero real numbers that satisfy the following equations: xy/(x+y)=a xz/(x+z)=b yz/(y+z)=c Is x rational? If so, express it as a ratio of two integers. Homework Equations I substituted a lot of equations...
  49. T

    Geometry and Discrete Mathematics notes? Resources?

    Geometry and Discrete Mathematics notes?? Resources? Hello everyone, I'm going to take Geometry and Discrete Mathematics, next year in high school (grade 12). So this summer I'm planning to read some books that would help me out next year, to bulit up my basic skills. So anyone know any sites...
  50. P

    Discrete Mathematics - Problems with Languages

    Let \Sigma = { \beta,x,y,z} where \beta denotes a blank, so x\beta \neq x, \beta \beta \neq \beta, and x\betay \neq xy but x \lambday = xy. Compute each of the following: 1: \parallel \lambda \parallel 2: \parallel \lambda \lambda \parallel 3: \parallel \beta \parallel 4...
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