5. Give an example of a family {Un new} of open subsets of R, with usual metric, such that new Un is not open.

Elements Of Modern Algebra
8th Edition
ISBN:9781285463230
Author:Gilbert, Linda, Jimmie
Publisher:Gilbert, Linda, Jimmie
Chapter1: Fundamentals
Section1.7: Relations
Problem 20E: Give an example of a relation R on a nonempty set A that is symmetric and transitive, but not...
icon
Related questions
Question
Please solve number 5
1. (X, d) is a metric space and A and B are subsets of X. Prove each
of the following if the boundary of a set A, denoted as bd(A), is defined
as bd(A) = An (X - A). Prove each of the following:
(i) bd(A) is a closed set.
(ii) A set A is closed if and only if bd (A) CA.
(iii) clA = Aº U bd.A.
(iv) If the metric d on X is the discrete metric, discuss the boundary
of a set AC X.
3. If G is an open dense subset of X, then X - G is nowhere dense,
where G is a non-empty proper subset of a metric space X.
4. Let U, V be subsets of a metric space X and V be open. Show that
if Un V = 0, then clUnV = 0.
"
5. Give an example of a family {Un new} of open subsets of R
with usual metric, such that new Un is not open.
Transcribed Image Text:1. (X, d) is a metric space and A and B are subsets of X. Prove each of the following if the boundary of a set A, denoted as bd(A), is defined as bd(A) = An (X - A). Prove each of the following: (i) bd(A) is a closed set. (ii) A set A is closed if and only if bd (A) CA. (iii) clA = Aº U bd.A. (iv) If the metric d on X is the discrete metric, discuss the boundary of a set AC X. 3. If G is an open dense subset of X, then X - G is nowhere dense, where G is a non-empty proper subset of a metric space X. 4. Let U, V be subsets of a metric space X and V be open. Show that if Un V = 0, then clUnV = 0. " 5. Give an example of a family {Un new} of open subsets of R with usual metric, such that new Un is not open.
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 2 steps with 2 images

Blurred answer
Recommended textbooks for you
Elements Of Modern Algebra
Elements Of Modern Algebra
Algebra
ISBN:
9781285463230
Author:
Gilbert, Linda, Jimmie
Publisher:
Cengage Learning,
Elementary Linear Algebra (MindTap Course List)
Elementary Linear Algebra (MindTap Course List)
Algebra
ISBN:
9781305658004
Author:
Ron Larson
Publisher:
Cengage Learning