Questions tagged [discrete-mathematics]

The study of discrete mathematical structures. Consider using a more specific tag instead, such as: (combinatorics), (graph-theory), (computer-science), (probability), (elementary-set-theory), (induction), (recurrence-relations), etc.

Discrete mathematics is not the name of a branch of mathematics, like number theory, algebra, calculus, etc. Rather, it's a description of a set of branches of math that all have in common the feature that they are "discrete" rather than "continuous".

The term "discrete mathematics" is therefore used in contrast with "continuous mathematics," which is the branch of mathematics dealing with objects that can vary smoothly (and which includes, for example, calculus). Whereas discrete objects can often be characterized by integers, continuous objects require real numbers.

Though there cannot be a definite number of branches of Discrete Mathematics, the following topics are almost always covered in any study regarding this matter −

  • Sets, Relations and Functions
  • Mathematical Logic
  • Group theory
  • Counting Theory
  • Probability
  • Mathematical Induction and Recurrence Relations
  • Graph Theory
  • Trees
  • Boolean Algebra

For an overview, see the Wikipedia entry on Discrete mathematics.

and http://www.cs.yale.edu/homes/aspnes/classes/202/notes.pdf

Consider using a more specific tag instead, such as: , , , , , , , , etc.

32903 questions
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How can I find $x$ having integer $f(x)$?

How can I find $x$ having integer $f(x)$? For example, when there are $f(x) = 5e^{-x}$ or $f(x) = -x + 6$ etc..., I want to find all x having integer $f(x)$. How can I find it? It doesn't matter if it's another function.
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Expressing "any value" vs "all values" in math

I'm trying to express the following sentence: "A condition is true when $X$ is greater than or equal to any value of $X_m$, where $m$ consists of $1,2,...$." (note: where $m$ stops is not known in advance) I've currently got that sentence expressed…
plu
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Trying to Understand the Meaning of Transitivity in Relation to a Particular Problem

I was trying to understand transitive relation and so I was solving a problem. The question is : $R_1 = \{(a,b)| a =b \text{ or }a = -b\} , R_2 = \{(a,b)| a =b \}, R_3 = \{(a,b)| a =b+1\}$, which one is transitive and why? As far as I know…
ktas
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Show that the following argument is valid.

Can anyone help me solve the above problem please? I am stuck for hours.
bsikriwal
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Discrete math: Is the survey accurate?

A library has conducted a survey of its readers. The survey asked its $10,000$ readers about their reading habits and the number of books that they have borrowed from the library in $2012$. It has found that its readers claimed to have borrowed…
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Discrete Math: Set Theory

Can anyone help me check if my solution is correct? Link here, sorry it kinda look too messy when i tried to paste d) A class has 175 students. The following table shows the number of students studying one or more of the following…
Natsume
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Two subsets of A that have the same number of elements and the same value of the sum of therir elements

It is A set of 100 integers between 1 and 1000000. Prove that there are (at least) two subsets of A that have the same number of elements and the same value of the sum of their elements. I need some help. I don't have idea.
Maria
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Using Rule of Inference to determine if conclusion is valid

Given: Every student has an email account Maggie does not have an email account Homer is a student Using E(x): x has an email, S(x): x is a student and M to represent Maggie while H represents Homer, I came up with the following…
Zevias
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Show whether the following statement in a tautology or a contradiction?

What I am given: [(p∧r)∧(p→ q)]→q What I did: ⇔ [(p∧r)∧( ¬p V q)] → q: Implication ⇔ ¬ [(p∧r)∧( ¬p V q)] V q: Implication ⇔ ¬ (p∧r) V ¬ ( ¬p V q) V q: De Morgan ⇔ (¬p V ¬r) V (¬ ¬p ∧ ¬q) V q: De Morgan ⇔(¬p V ¬r) V (p ∧ ¬q) V q: Double…
Zevias
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Solving $3$x $6$-sided dice of different colours to find the probability of events

An experiment consists of $3$ fair, different coloured dice being rolled. The dice are $6$-sided and the sides show numbers $1,\dots,6$. Let $A$ be the event that none of the dice shows numbers $1$ and $2$, and let $B$ be the event that all dice…
T. Mike
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Show that $| \{ 0,1 \}^{A} | = | \mathcal P(A) |$

Let $A$ be a set, and $ \left \{ 0,1 \right \}^{A}$ be the set of all functions $f$ from $A$ to $\left \{ 0,1 \right \}$ Show that $\left | \left \{ 0,1 \right \}^{A} \right | = \left | 2^{A} \right |$ We disccused this question on discrete math…
GoodWilly
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Set Builder Notation with a set of 2 tuple sets

I have a question regarding set-builder notation. I have a set {{0,1},{0,2},{0,3},...,{1,2},{1,3},{1,4},...,...}. I wrote this in set builder notation as {{x,y}|x,yεℕ∧y>x}. I've been told that its an incorrect form. If someone could explain to me…
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Proving irrationality by contradiction.

So I find solving proving irrationals with even numbers inside the square root like $\sqrt{2}$ easy which gives us even q and even p but when it comes to odd square roots or just straight out unknowns like $\sqrt{pq}$(yes they are 2 distinct prime…
oma
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is it good to use two Springer Discrete Maths books for math major?

Discrete Mathematics by Laszlo Lovasz, Jozsef Pelikan , Katalin L. Vesztergombi ISBN-10: 0387955852 A First Course in Discrete Mathematics (Springer Undergraduate Mathematics Series) ISBN-10: 9781852332365 are these two books suitable as Discrete…
Xingdong
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