4. Let {Ka}aeA be a collection of compact subsets of a metric space, Show NaEA K, is closed

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
Section: Chapter Questions
Problem 1RQ
icon
Related questions
icon
Concept explainers
Question
Question #4
Here is the transcription of the image for use on an educational website:

---

### Real Analysis and Metric Spaces Problem Set

#### 1. Metric Determination
Let \( x, y \in \mathbb{R} \). Determine if the following are metrics on \(\mathbb{R}\) or not:
   - (a) \(d_1(x, y) = \sqrt{|x - y|}\)
   - (b) \(d_2(x, y) = (x - y)^4\)

#### 2. Interior Points and Open Sets
Let \( E \subseteq X \) where \( X \) is a metric space. Let \( E^\circ \) denote all the interior points of \( E \). \( E^\circ \) is an open set—you don’t have to prove this, but you can use this fact to prove the following:
   - (a) Show \( E \) is open if and only if \( E = E^\circ \).
   - (b) Show: If \( G \subseteq E \) and \( G \) is open, then \( G \subseteq E^\circ \).

#### 3. Compact Subsets
Let \( K_1 \) and \( K_2 \) be compact subsets of a metric space \( X \). Show \( K_1 \cup K_2 \) is compact.

#### 4. Closedness of Intersection of Compact Sets
Let \(\{K_\alpha\}_{\alpha \in A}\) be a collection of compact subsets of a metric space \( X \). Show \(\bigcap_{\alpha \in A} K_\alpha\) is closed in \( X \).

#### 5. Non-compactness of Open and Compact Sets
   - (a) Consider the collection of open sets, \(\{(-n, n)\}_{n=1}^\infty\) in \(\mathbb{R}\) with the usual metric \( d(x, y) = |x - y| \). Use this collection of open sets to show \(\mathbb{R}\) is not compact (make sure to prove \(\mathbb{R} = \bigcup_{n \in \mathbb{N}} (-n, n)\) as part of your work).
   - (b) Give an example of a collection of compact sets in
Transcribed Image Text:Here is the transcription of the image for use on an educational website: --- ### Real Analysis and Metric Spaces Problem Set #### 1. Metric Determination Let \( x, y \in \mathbb{R} \). Determine if the following are metrics on \(\mathbb{R}\) or not: - (a) \(d_1(x, y) = \sqrt{|x - y|}\) - (b) \(d_2(x, y) = (x - y)^4\) #### 2. Interior Points and Open Sets Let \( E \subseteq X \) where \( X \) is a metric space. Let \( E^\circ \) denote all the interior points of \( E \). \( E^\circ \) is an open set—you don’t have to prove this, but you can use this fact to prove the following: - (a) Show \( E \) is open if and only if \( E = E^\circ \). - (b) Show: If \( G \subseteq E \) and \( G \) is open, then \( G \subseteq E^\circ \). #### 3. Compact Subsets Let \( K_1 \) and \( K_2 \) be compact subsets of a metric space \( X \). Show \( K_1 \cup K_2 \) is compact. #### 4. Closedness of Intersection of Compact Sets Let \(\{K_\alpha\}_{\alpha \in A}\) be a collection of compact subsets of a metric space \( X \). Show \(\bigcap_{\alpha \in A} K_\alpha\) is closed in \( X \). #### 5. Non-compactness of Open and Compact Sets - (a) Consider the collection of open sets, \(\{(-n, n)\}_{n=1}^\infty\) in \(\mathbb{R}\) with the usual metric \( d(x, y) = |x - y| \). Use this collection of open sets to show \(\mathbb{R}\) is not compact (make sure to prove \(\mathbb{R} = \bigcup_{n \in \mathbb{N}} (-n, n)\) as part of your work). - (b) Give an example of a collection of compact sets in
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 3 steps with 3 images

Blurred answer
Knowledge Booster
Continuous Probability Distribution
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, advanced-math and related others by exploring similar questions and additional content below.
Recommended textbooks for you
Advanced Engineering Mathematics
Advanced Engineering Mathematics
Advanced Math
ISBN:
9780470458365
Author:
Erwin Kreyszig
Publisher:
Wiley, John & Sons, Incorporated
Numerical Methods for Engineers
Numerical Methods for Engineers
Advanced Math
ISBN:
9780073397924
Author:
Steven C. Chapra Dr., Raymond P. Canale
Publisher:
McGraw-Hill Education
Introductory Mathematics for Engineering Applicat…
Introductory Mathematics for Engineering Applicat…
Advanced Math
ISBN:
9781118141809
Author:
Nathan Klingbeil
Publisher:
WILEY
Mathematics For Machine Technology
Mathematics For Machine Technology
Advanced Math
ISBN:
9781337798310
Author:
Peterson, John.
Publisher:
Cengage Learning,
Basic Technical Mathematics
Basic Technical Mathematics
Advanced Math
ISBN:
9780134437705
Author:
Washington
Publisher:
PEARSON
Topology
Topology
Advanced Math
ISBN:
9780134689517
Author:
Munkres, James R.
Publisher:
Pearson,