What Are Quotient Spaces and How Can We Visualize Equivalence Classes?

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Discussion Overview

The discussion centers on the concept of quotient spaces and how to visualize equivalence classes and equivalence relations, particularly in the context of mathematics and its applications in engineering and differential geometry.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • One participant inquires about the definition of quotient spaces and seeks a physical visualization of equivalence classes and relations.
  • Another participant explains that a quotient space is the set of equivalence classes and provides an example using the relation on R x R that leads to the visualization of a torus.
  • This explanation includes a description of how the plane can be visualized as being wrapped into a cylinder and then into a torus, highlighting the challenges of visualizing more complex quotient spaces.
  • A participant with a background in engineering and currently studying differential geometry acknowledges the explanation and expresses intent to explore the topic further.
  • Another participant expresses confusion regarding the group theory aspect mentioned and requests guidance on the appropriate order for taking math courses, emphasizing a preference for applied mathematics over pure mathematics.
  • One participant suggests to disregard the group theory example, noting that equivalence classes and relations are prevalent in various areas of mathematics.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and familiarity with the concepts discussed. There is no consensus on the necessity of group theory in understanding equivalence classes, and some participants seek clarification on the relevance of different mathematical backgrounds.

Contextual Notes

Some participants indicate a lack of familiarity with group theory and its relation to equivalence classes, which may affect their understanding of quotient spaces. There is also a mention of the need for practical applications in engineering, suggesting a limitation in the focus on pure mathematical concepts.

shankarvn
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Hi

I just wanted to know what a qoutient space is . Is there a physical picture to it? How can one imagine what an equivalence class,equivalence relation is?
 
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The quotient space is the set of equivlance classes. How one pictures it, if one should even bother doing so depends on the context.

Given where you've posted this, I guess you mean things like:

Consider RxR with the relation (x,y)~(u,v) iff x-u and y-v are integers.

With experience, you instantly notice that is the torus.

How? Imagine the plane. We identify firstly all the x coordinates with the same non-integer component, and as we go from 0 to 1 we 'wrap' round again to 0, so that's like rolling the plane up into a big cylinder. similiary in the y direction we wrap the cylinder into itself.

Obviously for more complicated examples we can't even picture the initial space, never mind using that to construct the quotient space in our heads.


An equivalence class is the set of all points that are equivalent under an equivalence relation. again, experience is the best thing here.

An equivalence relation is the same thing as a partition of a set.

What are the equivalence classes of some group G when the relation is x~y if there is a z such that zx=yz?

Can you show that's an equivalence class?

It'd help to know what level of material you're used to.
 
Hi

I am doing a course in differential geometry. I have an engg back ground. The concept of quotient spaces comes every now and then in our class. Your explanation does give a picture. I will read more and get back to you. Thanks
Shankar
 
Hi
I did not follow whatever you said about groups. I have no clue as to what a group is though I have encountered that also before. I have not seen the group interpretation of equiv classes. I have seen equiv classes being defined in order to define a quotient space. Could you tell me what is the right order to take math courses. I do not or probably I cannot take too much of pure math. I need to apply this stuff in engg. Thanks
 
Forget the group stuff. Equivalence classes and relations come up in lots of mathematics, and that was another *example* of one.
 

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