For reflexive, symmetric and transitive relations. Use it with the tag (relations).

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1answer
102 views

Solve for ? - undetermined inequality symbol

So I was solving a problem in Rudin (chapter 3 #16, to be specific) and I realized how convenient it would be to have a symbol that represented an undetermined equivalence relationship. As an example ...
3
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1answer
80 views

Proving $R$ is a Equivalence Relation?

The Relation: $\left\{R = ((m, n) |\ mn \geq 0\ \right\} on \ \mathbb{Z}$ apparently has an equivalence class. I can't really see it, I can see that reflexive does not fail. From the looks for it, ...
2
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1answer
41 views

A relation that is Reflexive & Transitive but neither an equivalence nor partial order relation

Set $A = \{0,7,1\}$ 1. So for a relation that is reflexive and transitive but neither an equivalence relation nor partial order...Can a relation be both partial order and equivalence? Attempt: ...
2
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1answer
152 views

equivalence relation composition problem

Let $R_1$, $R_2$ be two equivalence relations on $X$, prove that $R_1\circ R_2$ is an equivalence relation if and only if $R_1\circ R_2= R_2\circ R_1$ First I´m trying to prove that $R_1\circ R_2= ...
2
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1answer
22 views

What is the structure of a directed graph with vertex set A which has a relation R

I am studying for a test and found this question in the book: Let $R$ be an equivalence relation on the set A (Non-empty). Let $D_R$ be the directed graph with vertex set $A$ and an arc from $x$ to ...
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1answer
13 views

Verify Equivalence relation.

Question: Find an example of three relations $R_{1}$, $R_{2}$ , $R_{3}$ on the set S=$\{1,2,3,4,5\}$ such that $R_{1}$ is reflexive but not transitive, $R_{2}$ is transitive but neither symmetric ...
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1answer
49 views

$\sin(x)$ is asymptotically equal to $x+5x^3$

Here is my question: I've never seen before this kind of fact underlined about asymptotic equalities (and why we keep only one term in these equalities) and I'm looking for reference. Here is an ...
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1answer
17 views

Proving Equivalence Relations and Quotient Sets

Prove that the relation ∼ on $Z×Z$ given by $(a, b) ∼ (c, d)$ if $a+d = b+c$ is an equivalence relation. Give the quotient set $Z × Z/$ ∼.
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1answer
42 views

Is the property reflexive, symmetric, anti-symmetric, transitive, equivalence relation, partially ordered given the relation below?

I'm working on this and I'm supposed to figure out if the following properties apply to the below relations. Properties are: ...
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171 views

Colored Picture for Equivalence Classes, Relations, Partitions, ..

Origin — A Book of Abstract Algebra — Charles Pinter — p120. I'm trying to sketch a colored picture for the ideas from equivalence classes, equivalence relations, partitions, etc... underneath. ...
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39 views

Relationship between 2 sinusoidal signal data sets?

I'm trying to relate a near shore tidal signal (point A) to 3 points along a long model boundary (points B C D). I want to possibly have a relationship between B C D with which we can convert A ...
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0answers
43 views

Good topologies on $\mathcal{P}(X)$

Let $X$ be a topological space, and let $\mathcal{P}(X)$ (resp. $\mathcal{P}_0(X)$) be the set of all subsets of $X$ (resp. the set of all non empty subsets of $X$). Finally, let ...
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39 views

Equivalence of Two Different Irrational Numbers Converse

Equivalence of Two Different Irrational Numbers I came across this and follow the proof, but I'm wondering how you would prove the converse, that is, if 2 irrational numbers are equivalent then their ...
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0answers
19 views

prove the following equivalence $\ln(-\frac{l-x+\sqrt{r^2+(l-x)}}{l+x-\sqrt{r^2+(l+x)}})={}$ArcSinh$(\frac{l+x}{r})+{}$ArcSinh$(\frac{l-x}{r})$

Hi guys i'm trying to prove the following equivalence but i'm having some problems: $$\ln\left(-\frac{\ell-x+\sqrt{r^2+(\ell-x)^{2}}}{\ell+x-\sqrt{r^2+(\ell+x)^{2}}}\right) = \operatorname{ArcSinh} ...
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25 views

Axioms of equivalence relation in terms of the subset $R$

..An equivalence relation on $S$ is determined by the subset $R$ of $ S \times S$ consisting of those pairs $\left(a,b\right)$ such that $a \sim b$. Write the axioms for an equivalence relation in ...
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0answers
29 views

A partial order with more properties than would be expected

Consider the relation: $$\langle x_1,x_2\rangle\prec\langle y_1,y_2\rangle\iff x_1,x_2,y_1,y_2\in\Bbb N\wedge x_1y_2<x_2y_1.$$ This is usually used for defining the (positive) fractions $\Bbb ...
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35 views

Prove/disprove questions on equivalence relations and ordered sets

If $R$ is an equivalence relation and a partial order over $A \neq \emptyset$ then every equivalence class contain at least one element. If $(A,\le)$ an ordered set, and $a\in A$ is a single ...
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77 views

Improper integral calculation and nature

I would like to know how to calculate this integral n check its nature : $$ A= \int_1^\infty \frac{e^{-t}}{1+t^{2}} dt . $$ I think I figured it out , we can do it with Equivalence like this (since ...
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82 views

Power Set, Bijection Function, Equivalence Relation

Let $S$ be a set and $P(S)$ the power set of $S$. For sets $A,B⊆P(S)$, we say that $A \sim B$ if there exists a bijective function $f: A \rightarrow B$. Show that $\sim $ is an equivalence relation.
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On $N \times N $ define the relation R, setting $(a,b),(c,d) \in R$ if and only if $a+d=b+c$. Show that $R$ is an equivalence relation.

On $N \times N $ define the relation R, setting $(a,b),(c,d) \in R$ if and only if $a+d=b+c$ a. Show that $R$ is an equivalence relation. My attempt: By definition 6.2.3 $R$ is an equivalence ...
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25 views

What does a null relation on all real numbers look like?

I'm being asked to test for reflexivity, symmetry, transitivity, and antisymmetry on a null relation for all real numbers, i.e. $X=\mathbb{R}; R = \emptyset $. What would such a resulting set look ...
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33 views

Equivalence Set, Subsets

Just a quick question: If a = [A] and a belongs to N (set of all natural numbers) doesn't that mean that A is a subset of N? The reason I'm asking this is because I'm trying to prove the theorem ...
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34 views

The null set as the underlying set of a relation structure

Can the null-set underly a relation structure? Can it underly a well-order? If so, would such a well-order have order-type $0$? (Can one even have an order-type of $0$?) My motivation for this ...
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32 views

Prove that $[x]_{R}=[y]_{R} \Rightarrow g(f(x))=g(f(y))$

Let $f:\mathbb{Z} \to \mathbb{N}$ and $g:\mathbb{N} \to \mathbb{N}$ be functions. And let $R$ be a equivalence relation on $\mathbb{Z}$, defined by: $$xRy \Leftrightarrow f(x)=f(y)$$ For any ...
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28 views

Finding equivalence relations containing specific equivalences

"Find the number of equivalence relations on the set $\{1,2,3,\ldots,7\}$ such that: a) $1\sim2$ and $3\sim4$. b) $1\not\sim2$, $1\not\sim3$ and $3\not\sim2$." Solving this problem is equivalent to ...
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34 views

Congruence induced by a subset.

Consider the additive monoid of natural numbers and calculate the congruence generated by $\{(2,3)\}$. I know the answer is that the congruence has 3 classes which are $\{0\}$, $\{1\}$, and the rest. ...
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25 views

How I can define an equivalence relation on the graph of a function?

Let $a∈ℝ$ being fixed. Let $g:ℝ→ℝ$ be a real analytic function with infinitely many zeros. I want to classify the points $c,d$ such that $g(a)=(a-u)g′(c)≠0$ and $g(a)=(a-w)g′(d)≠0$ where $c∈(u,a)$ and ...
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79 views

Finding correct equivalence matrix for all group representations

This question is linked to a previous one that I asked: Attempting to find a specific similarity (equivalence) matrix I have a group of 24 elements, with two generators. I need to find an ...
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164 views

Attempting to find a specific similarity (equivalence) matrix

Apologies if this has already been asked - I searched but couldn't find. My question is regarding matrix similarity (equivalence): I have a square matrix $A$ that is of permutation form and (square) ...
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40 views

Spherical Grid Identifcation

I'm trying to see how the lower half of these grids look like when I make the following identification onto the unit sphere: CLICK HERE TO SEE IMAGE In notation, how would one represent this ...
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51 views

Simple counting question related to equivalence classes

Let $S = \{1,2,3,...,10\}.$ Define the relation $\mathscr R$ on the power set $\mathscr P(S)$ of all subsets of $S$ by: for all $A,B \in \mathscr P(S),A\mathscr RB$ if and only if $N(A) = N(B)$. ...
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Prove that the following relation is an equivlance relation.

Prove that the following relation is an equivalence relation and determine how many equivalence classes R partitions the set $Z^{+}$ into. R = {$(a,b) | a∈Z^{+} ∧ b∈Z^{+} ∧ 10 | (a^{2}- b^{2})$} Any ...
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85 views

Function on equivalence relation on functions

Let $E$ be the set of all functions from a set $X$ into a set $Y$. Let $b \in X$ and let $R$ be the subset of $E \times E$ consisting of those pairs $(f,g)$ such that $f(b) = g(b)$. Prove that $R$ is ...
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70 views

wikipedia relation algebra example #3

Wikipedia article gives the following relation algebra example: 3 An important generalization of the previous example is the power set $2^E$ where E ⊆ X² is any equivalence relation on the set X. ...
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37 views

Properties of relations on Z

$$R_3 = \{(x,y) \in \mathbb{Z} \times \mathbb{Z}|\frac{x-y}{5} \in \mathbb{Z}\} $$ $$R_4 = \{(x,y) \in \mathbb{Z} \times \mathbb{Z}|x > y \} $$ I need to know which one is reflexive, symmetric, ...
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36 views

Divisibility: a partial order

Why is divisibility on the set of integers only a partial order and not a total order? I know total order requires the additional requirement of: For any $a,b \in S$, either $a\le b$ or $b\le a$. But ...
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33 views

Transitive, Reflexive, Symmetric

So i know what each of these properties are..but this question does not provide any information on a 3rd variable so i was wondering how i would do it? ...
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25 views

A proper term for equivalence relation with a finite quotient set

Is there a proper term for an equivalence relation $\sim$ on some set $M$ such that it partitions $M$ into finitely many equivalence classes? Finite equivalence relation? or co-finite? or equivalence ...
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97 views

About Kernel and the coimage of a function

Introduction I was serching for a concept of "equivalence relations" induced by an arbitrary function in a "natural" way and I found the concept of Kernel. But I'm not sure that I understand it and ...
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30 views

Prove congruence relation.

Let $\sim$ be a relation where $x \sim y \Leftrightarrow x = y \lor (x \in I \land y \in I)$. Show $\sim$ is a congruence relation on $S$ where $S= \{a,b, c, d, e\}$ and $I = \{a, d\}$. One of the ...
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21 views

Question about Equivalence relation and partition

This is my first time of Abstract algebra, and I don't know how to solve this problem. Although I have an idea to solve this problem, I can't assure whather it is correct or not. Please show me how ...
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20 views

Bijection between partial order and $<$

How to show the correspondence between a less than relation and partial orders ? here A less than relation $<$ on a set $S$ is a relation that satisfies If $a < b$ , then $a \neq b$. ...
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36 views

Prove that $R_1$ refines $R_2$ if and only if the partition with respect to $R_1$ is a refinement of the partition with respect to $R_2$.

Let $R_1$ and $R_2$ be equivalence relations on a set $S$. Prove that $R_1$ refines $R_2$ if and only if the partition with respect to $R_1$ is a refinement of the partition with respect to $R_2$. ...
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31 views

Is an equivalence class same as residue class?

So my teacher's notes say this: An equivalence class consists of those integers which have the same remainder on division by n. They are also known as "congruence classes modulo n" Since ...
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15 views

What kind of relation does an ambiguous organization scheme introduce?

Please consider an arbitrary set of items, i.e. products in a supermarket or news in a news channel. Let's say we want to apply an organization scheme to that items. There are unambiguous ones, like ...
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36 views

A question on Partitioning regarding equivalence relations

Let $S$ be the Cartesian coordinate place $\mathbb R \times\mathbb R$ and define the equivalence relation $R$ on $S$ by $(a,b) R (c,d)$ iff $b-3a = d-3c$ Find the partition $D$ determined by $R$ by ...
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60 views

What is this equivalence relation explicitly?

Let $S \colon = \{ \ (x,y) \in \mathbf{R}^2 \ | \ \ y = x +1, \ \ 0 < x < 1 \ \}$, and let $T$ be the intersection of all the equivalence relation on the plane that contain $S$. Then how ...
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35 views

How does Dilworth’s Theorem apply to the set {0, 2, 6, 7}?

I'm having some serious problems with Dilworth's Theorem. My question is 'how does Dilworth’s Theorem apply to the set {0, 2, 6, 7}?'. Any help is appreciated.
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43 views

Suppose $R$ is an equivalence relation and define $[x]_R=\{y:\langle x,y\rangle \in R\}$

I am not sure if I have approached this the right way, or if my approach demonstrates an appropriate grasp of the question being asked. Any help would be most appreciated. (I also hope that I've ...
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43 views

Please help to clarify this passage from Folland Analysis - equivalence relation example

I can not picture the equivalence class from this one. Thus I can not understand the later part which proves "every x belongs to one Nr". Please help me to clarify this example.