Show that the quotient space is Compact and Hausdorff

In summary: R}^n / \sim. This map is continuous and bijective and thus a homeomorphism.In summary, the conversation discusses the proof that the quotient space \mathbb{R}^n / \sim is Hausdorff, compact, and homeomorphic to (S^1)^n, given that the set of n-linearly independent vectors w_1,...,w_n are defined and an equivalence relation \sim is defined by p\sim q \iff p-q=m_1w_1+...+m_nw_n for some m_i \in \mathbb{Z}. The speaker explains the steps taken to prove the quotient space is Hausdorff
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Homework Statement


Let [itex]w_1,...,w_n[/itex] be a set of n-linearly independent vectors in [itex]\mathbb{R}^n[/itex]. Define an equivalence relation [itex]\sim[/itex] by
[itex]p\sim q \iff p-q=m_1w_1+...+m_nw_n[/itex] for some [itex] m_i \in \mathbb{Z}[/itex]
Show that [itex]\mathbb{R}^n / \sim [/itex] is Hausdorff and compact and actually homeomorphic to [itex](S^1)^n[/itex].



The Attempt at a Solution


I first showed that the quotient space was Hausdorff by showing that the set [itex]\{(x_1,x_2): x_1\sim x_2\}[/itex] was closed in [itex] \mathbb{R}^n \times \mathbb{R}^n[/itex] and that the quotient map was an open map. Using a result I proved earlier in the assignment as well as this, I was able to conclude the quotient space was hausdorff.

It is proving Compactness where I get stuck. So far I have made no progress. Any advice would be much appreciated.

Homework Statement

 
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  • #2
Let w_1,...,w_n be a set of n-linearly independent vectors in \mathbb{R}^n. Define an equivalence relation \sim by p\sim q \iff p-q=m_1w_1+...+m_nw_n for some m_i \in \mathbb{Z}Show that \mathbb{R}^n / \sim is Hausdorff and compact and actually homeomorphic to (S^1)^n.The Attempt at a SolutionI first showed that the quotient space was Hausdorff by showing that the set \{(x_1,x_2): x_1\sim x_2\} was closed in \mathbb{R}^n \times \mathbb{R}^n and that the quotient map was an open map. Using a result I proved earlier in the assignment as well as this, I was able to conclude the quotient space was hausdorff.For compactness I am using the fact that a finite product of compact spaces is compact. This means I must show that each of the quotient spaces \mathbb{R}/ \sim_i is compact. For each of these, I will show that they are closed and bounded in \mathbb{R}. To do this I will use the fact that the equivalence classes can be written as m_iw_i + k where m_i is an integer and k is a vector in \mathbb{R}^n. This leads to the conclusion that the quotient space is of the form \{z+k : z \in \mathbb{Z}\} which is clearly both closed and bounded in \mathbb{R}. Finally I need to show that \mathbb{R}^n / \sim is homeomorphic to (S^1)^n. To do this I consider the map \phi: \mathbb{R}^n / \sim \rightarrow (S^1)^n defined by \phi([x]) = [e^{2\pi i x_1},...,e^{2\pi i x_n}] where [x] is the equivalence class
 

Related to Show that the quotient space is Compact and Hausdorff

1. What is a quotient space?

A quotient space is a mathematical concept used in topology to define a new space from an existing space by identifying certain points as equivalent or "collapsed" together. This results in a space that is smaller or more simplified than the original space, but still retains important topological properties.

2. How can I show that a quotient space is compact?

To show that a quotient space is compact, you can use the fact that a space is compact if and only if every open cover of the space has a finite subcover. So, you can start by assuming that your quotient space is not compact and constructing an open cover that does not have a finite subcover. Then, by using the properties of quotient spaces, you can show that this open cover must have a finite subcover, proving that the quotient space is compact.

3. What does it mean for a space to be Hausdorff?

A space is Hausdorff if for every pair of distinct points in the space, there exist disjoint open sets containing each point, respectively. This means that in a Hausdorff space, points can always be separated by open sets, providing a stronger notion of separation than just being in different neighborhoods.

4. How can I prove that a quotient space is Hausdorff?

To prove that a quotient space is Hausdorff, you can use the fact that quotient spaces preserve the Hausdorff property. This means that if the original space was Hausdorff, then the quotient space will also be Hausdorff. So, you can start by showing that the original space is Hausdorff, and then use the properties of quotient spaces to show that the quotient space must also be Hausdorff.

5. Are there any other important properties of quotient spaces?

Yes, there are several other important properties of quotient spaces, including being connected, being locally connected, and being path-connected. These properties also tend to be preserved under the process of taking a quotient space, so they can be useful in proving other properties or characteristics of quotient spaces.

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