Hi all,Let λ>0 and define an equivalence relation on

In summary, the conversation discusses the definition of an equivalence relation on the set of real numbers excluding 0, and the desire to understand the quotient space ℝn-{0}/~. The conversation also explores how this works for n=1 and the goal of showing that the quotient space is homeomorphic to S1 x Sn-1. There is also a request for help in understanding quotientspace and how to specify equivalence classes for elements in certain intervals.
  • #1
Jooolz
14
0
Hi all,

Let λ>0 and define an equivalence relation on ℝn-{0} by

(x~y) [itex]\Leftrightarrow[/itex] (there is an s[itex]\in[/itex]Z such that λsx=y)

I would like to know what the quotient space ℝn-{0}/~ looks like. I know that it is a set of equivalence classes.

To understand it better I wanted to see how it works for n=1. In that case I found that for all a[itex]\in[/itex] (1, λ] there is an equivalence class [a]. And for b[itex]\in[/itex] (λ, λ2] we have b=rλ where 1< r ≤ λ. But this means that b~r. So b[itex]\in[/itex][r] and we know that r[itex]\in[/itex] (1, λ]. The same idea holds for elements from the intervals (λi, λi+1]. Hence every element from (1, ∞) will be in an equivalence class which has a representative in (1, λ]. Am I seeing this correct?

But how can I specify the equivalence classes of the rest of the elements of ℝ-{0}? (since λ > 1)

The goal is, (eventually) to show that the quotientspace ℝn-{0}/~ is homeomorphic to S1 x Sn-1.

I would really appreciate any help or hints, to make me understand better what they mean by quotientspace.

Kind regards,
J.
 
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  • #2


For elements in ]0,1[, you can show that such elements are also equivalent to an element in [itex][1,\lambda[[/itex]

For elements in [itex]]-\infty,0[[/itex], you can show it equivalent to something in [itex]]-\lambda,-1][/itex].
 

1. What is λ and why is it defined as greater than 0?

λ is a mathematical constant known as the wavelength. It is defined as greater than 0 because it represents a distance or length, which cannot be negative.

2. What does it mean to define an equivalence relation?

An equivalence relation is a mathematical concept that establishes a relationship between two elements or sets. It is used to classify objects as being equivalent or not equivalent based on certain criteria.

3. How is the equivalence relation defined for λ>0?

The equivalence relation for λ>0 is defined as a relation between two elements, where the elements are considered equivalent if they have the same wavelength, or distance, of λ. In other words, if two elements have the same value of λ, they are considered equivalent under this relation.

4. What are some examples of objects that can be classified using this equivalence relation?

Some examples include waves, such as sound waves or electromagnetic waves, where the wavelength is an important characteristic. Other examples could include objects with a specific length, such as musical instruments or objects in a geometric shape with a defined perimeter.

5. What is the significance of defining this equivalence relation?

Defining an equivalence relation allows us to categorize and compare objects based on a specific characteristic, in this case, the wavelength. It can help us better understand patterns and relationships in various fields such as mathematics, physics, and engineering.

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