Equivalence Relation and the Unit Circle: Understanding R/Z and S^1

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Homework Help Overview

The discussion revolves around the concept of equivalence relations in the context of the real numbers and the unit circle, specifically examining the relationship between R/Z and S^1. Participants are exploring how the equivalence relation defined by Z acting on R leads to the identification of points and the implications for the structure of R/Z.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning the nature of the equivalence relation and its effect on the interval [0,1]. There is a discussion about how points 0 and 1 are treated as equivalent, leading to the idea of bending the interval into a circle. Some participants express confusion about the relationship between R/Z and S^1, particularly regarding the length and properties of the intervals involved.

Discussion Status

The discussion is ongoing, with participants actively questioning the definitions and implications of the equivalence relation. There is a recognition of the need to clarify why R/Z is described as S^1, and various interpretations of the intervals are being explored without a clear consensus.

Contextual Notes

Participants note that the interval should be considered as [0,1) and discuss the implications of including or excluding endpoints in the context of the equivalence relation. There is also mention of the length of the interval in relation to the circumference of the unit circle.

pivoxa15
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Homework Statement


If Z acts on R by n.x=n+x then R/Z is just S^1. CLaims the book

But I think R/Z is (0,1)


The Attempt at a Solution


Any number greater than or equal to 1 is dealt with by the equivalence relation. How does the unit circle come into it? We are dealing only with one dimensional space here.
 
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Because the points x=0 and x'=1 are identified as the same point in R/Z?
 
pivoxa15 said:

Homework Statement


If Z acts on R by n.x=n+x then R/Z is just S^1. CLaims the book

But I think R/Z is (0,1)


The Attempt at a Solution


Any number greater than or equal to 1 is dealt with by the equivalence relation. How does the unit circle come into it? We are dealing only with one dimensional space here.
That's the whole point- the equivalence relation makes 0 and 1 equivalent- you are bending [0,1] (not (0,1)) back on itself so it becomes a circle.
 
Actually the interval should be [0,1) so if you include 1 then 1 is 0 so it bends back on itself. However they described it as S^1. Why S^1? That is the unit circle with radius 1. So has circumference 2pi. But our interval has length 2pi?
 

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